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1995 164Q air conditioning

4K views 29 replies 8 participants last post by  GTV67 
#1 · (Edited)
Yesterday was the first really warm day of the year here in Northern California - I drove home 40 miles with the a/c working fine.
But, today it doesn't work at all - I can't hear the compressor kicking on, I see a telltale streak of "something" on the gravel under the left-engine bay underside where I parked when I got home.

I live at the top of a really steep hill, so I'm guessing something bad happened climbing the hill, it puked out the a/c fluid at the top, and now I have low fluid pressure.

Checking around the engine bay this afternoon:
- On the left side engine bay all I'm aware of are the unions into the a/c radiator - and both look tight with no tell-tale green stuff sprayed out. But that could be misleading, the bottom one is hard to get a good view.
- I can see one or two drips of green liquid formed under the left driveshaft. I would have guessed coolant dripping from coolant reservoir underside, but maybe a/c fluid?
- the a/c fuses all look fine - the big 40A one behind the firewall and the 10A ones in the fuseboxes
- lines on rear of compressor all look clean and dry
- same for components on right fender and in front of passenger windshield - all dry

So questions:
- if the fluid pressure is low, does that stop the compressor kicking on?
- if the engine suddenly ran hot (climbing final hill) could that cause extra pressure in the a/c fluid somehow and trigger a leak?
- is there anything other than radiator unions on the left side of the engine bay that is a/c related?
- does a/c fluid vanish when it leaks? or should I see telltale signs?
- any tips for a/c system sealing? where to look for most common leaks etc.

Thanks for any leads,

-Richard
Santa Cruz, CA
 
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#2 · (Edited)
At first guess, it sounds more like two separate unrelated issues, ie, engine coolant loss, such as from a leak at a hose connection, or a crack in the overflow tank (a common problem), and separately, perhaps low a/c 134a fluid.

The a/c 134a fluid evaporates away if it leaks. The engine coolant just drips onto the ground.

Check again for engine coolant leaks, and add more 50/50 coolant and see what happens to the level upon further driving. You may have to pull the overflow coolant tank to check it for cracks. Just might be a loose small hose connection underneath the tank, judging by the described location of the drips under the lhs of the car.

Buy one of the a/c 134a fluid cans with the attached fitting and valve for do it yourself topping up of the a/c system, or, if you would rather, take the car to an a/c shop and have the a/c fluid level checked and topped up if low. Buy the fluid with the stop leak additive if you choose to check it yourself. The a/c pump will not turn on if the fluid is low.

My 91S, converted to 134a, developed a very slow leak, and two cans of the fluid with stop leak did the trick. Hopefully it might in your case as well, but of course, no guarantees. The pressure in my car has held through the winter for several years so far. The only problem I've had with the a/c in my 94LS was the a/c pump clutch shorting out (same as happened in our 91S), requiring replacement. In the case of that clutch shorting out, the 10A fuse will always blow. Obviously not your problem (yet).

Others with more 164 a/c experience will most likely chime in and add more suggestions.
 
#3 · (Edited)
Does the a/c blower fan motor work now?

I suggest you put a set of a/c servicing gauges/manifold with hoses on the low and high side of system to see if you have any R134a Freon in the system.
 
#4 ·
Thanks Del, thanks Steve,

it dawned on me reading Del's message that the dye in the a/c fluid can only be seen with a black light, which I don't have - so maybe it's all over the bottom port on the radiator and I can't see it.

I bought a couple of 12oz cans of R134a (with leak sealer) today and a short hose/gauge for just the low pressure side. But I won't be able to try them until the weekend - definitely a session of going around the engine-bay tweaking unions before I try that.

Steve, I should get a proper set of hi/low pressure gauges, agreed that's the right thing to do. Yes the blower motor runs. I certainly had plenty of freon Tuesday evening, but not necessarily any on Wednesday morning.

Thanks,

-Richard
 
#5 ·
Summer vacations intervened therefore no progress on this until today.

Started the car - ran with a/c on 'lo' -

as far as I can tell all fuses are good - the compressor was engaging/disengaging - I tried unplugging/re-pugging the red 2-pin connector at the base of the windshield and heard the compressor engage/disengage as I did so.

therefore attached gauge to low-pressure port, saw about 30 psi (just in the "green") on the cheapo filler gauge - therefore emptied 2 x cans of R134 into it and saw that pressure rise to more like 50psi.

compressor was cycling, blower motor was blowing, fluid pressure (low side only) seemed good - but...nothing but warm air out of the vents.

This system has definitely worked when charged by a real A/C machine - therefore not sure what might have gone wrong here - of course the fluid could all have leaked out but as I filled it today, the pressure rose with no sign of leaks - yet still no cold air again.

Any suggestions where to look next?

Thanks,

-Richard
 
#6 ·
The R134a system on the 164 takes 44 oz. Two cans would be 24oz but I doubt you were able to get more than 20 in the system.

That being said I suggest you take car to real a/c shop for diagnostic testing with the "real" a/c machine with dye, PAG oil, and R134a.

I suspect you have a front seal on compressor crankshaft leaking. If dye already in system the black light will show the dye on compressor clutch plate in center of belt pulley.

Point of info: When system fully charged and compressor not engaged, the low pressure side at rest will show about 80 psi and then when clutch engaged gauge will pull down to about 30 psi at idle and maybe lower at fast engine idle.

Unless you are set up with proper gauge set, dye, black light and vacuum pump, etc... and the know how
 
#9 ·
Unless you are set up with proper gauge set, dye, black light and vacuum pump, etc... and the know how
Totally agree and will do as you all suggest - take it to an A/C shop. I don't understand this system well enough and don't have the tools. I didn't know the front seal was the likeliest leak point, good to know.

I'm still a bit thrown by it working so well for a month then being busted next day - and seeing the stripe of fluid on the driveway behind the left front wheel - before I started yesterday I did tighten the lower union on the A/C heat exchanger - hoping that might be the leak-point and worth an attempt at re-charging. But lesson learned. There is dye in the system so the guy's black light will hopefully reveal where it's leaking.

Thanks to all.

-Richard
 
#7 ·
Cease fire. You're "fiddling" with the system and likely to do more harm than good. If you want to service the system yourself, you need knowledge of how this particular system is designed to operate, and tools . . . like the basic tool to diagnose and service a system . . a gauge set. That cheapo chicom gauge attached to the R134a can is worse than worthless. It leads people into thinking they know what they're doing when they don't.

I don't have any experience on the Q, but AFAIK the Q has the same A/C system as the S and LS. It is a system that incorporates a Pilot Operated Absolute (POA) valve that prevents evaporator freezing by bypassing excessive pressure. The POA valve is that can-like thing that sits on the right front inner fenderwell connected by the two return hoses. In this type of system the compressor runs continuously. So, if your compressor is cutting in and out, there's something wrong. Most likely low gas, which means a leak . . and the most likely suspect is the compressor front seal.

Dumping a bunch of refrigerant into the system willy-nilly can lead to overcharging and overpressures that actually reduce cooling and damage components. I also highly resist using stop-leak in A/C systems.
 
#10 · (Edited)
Point of info: Your "a/c heat exchanger" in front of radiator is called the a/c condenser and the unit inside the black box behind the false firewall is the a/c evaporator.

On top of the evaporator box is the a/c expansion valve attached to both the evaporator coil and the black cylinder known as the receiver dryer which has the a/c low/high pressure switch screwed on the end of it.

The low pressure side of the switch allows the compressor clutch relay IF the R134a system pressure is sufficient to engage the compressor clutch.

When the high pressure reaches 215 psi in a/c system switch will engage the radiator fan relay.
 
#11 ·
A couple of points: there is usually a high/low-pressure switch in the system. When the pressure gets to the max the compressor kicks out, and when it gets to the low level, the switch kicks the compressor on. This is why you hear the clutch cycling on and off. When the refrigerate gets to low, the low side switch will not kick on. A qualified A/C mechanic can diagnose what is wrong and recommend a fix. The gauges will tell a lot about what is happening. The Sanden compressor can be rebuilt if you can not find a new one. Usually, the seal on the shaft goes bad and the fluid evaporates out. If this is the case you should switch over to R134A and PAG oil. New seals on the connections will be needed.
Report back as we can all learn what your situation was.
 
#12 · (Edited)
By the time the Q came to be, Alfa had switched over to R-134a. New compressors are readily available, however, SAVE THE ORIGINAL PULLEY. You'd need to reuse that. If opening the system to replace the compressor or the front seal, I'd highly recommend that the condenser be replaced with a modern parallel flow type. It's something like 30% more efficient than the OEM one.

This should be the part you'd need, but should check with the service guy. It requires making a couple "feet" for it and trimming a few pieces of plasticwork, but works much more efficiently than the OEM condenser. Full write up for fitting it is in the 12v R-134a Conversion Guide.

I'm not certain this applies to the Q, but I'm betting it does . . .
VERY IMPORTANT NOTE: It's likely that if your service guy has to remove the compressor, he's going to be extremely miffed (not the language that he'll use BTW) when he can't get the long top bolt out because it hits the body work before it comes out enough to remove. The reason for this is the engine was installed in the car with the compressor attached and the engineers did not see the service problem that would arise later. They could have specified installing the bolt the OTHER way and it would be no problem, but they didn't. Now it's the mechanics problem. See page 5 of the Conversion Guide, for a picture of the issue. You DON'T want the mechanic to get all the way down to removing the compressor only to find out about this issue and having the car in pieces until a new bolt can be obtained. Get it first, then start work, assuming he has to remove the compressor.

The solutions are:

1. Jack the engine up enough to clear the inner fenderwell. Time consuming and expensive. Not recommended.

2. Beat the fenderwell down to the point the bolt can be removed. Not recommended either. We don't beat our cars with nine pound hammers.

3. Cut the bolt and install a new one. Best solution, BUT, make sure you have a replacement on hand. That metric bolt is available (10mm diameter x 1.25 pitch x 170-175mm long (1.5 pitch will work also, but you'll need the correct nut too), but probably only from a specialty fastener supplier. An inch spec bolt is commonly available 3/8" and could be used in a pinch, but is slightly small in diameter. As long as the compressor is pushed all the way against the engine and then tightened, it should work ok until a correct bolt can be sourced.

4. Cut the bolt head off, and pull it through from the driver's side. Then center weld a nut onto the cut end. This is pretty backwoods ******* ugly, but would probably work.

https://www.alfabb.com/bb/forums/164-168-1991-1995/198765-r-134a-conversion-guide.html

https://nostalgicac.com/16-x-22-superflow-r-134a-condenser.html
 
#13 ·
Thanks Roadtrip and Veloce - and very well noted about the long bolt. If we get to that stage then it will be me doing the compressor removal/re-install. I remember having this exact thought about that bolt when I was re-assembling the engine before re-install.

And thanks Steve et al for the system explanations. Yes I'll report back if/when I ever fix it.

-Richard
 
#14 ·
Following the information provided here I've been ordering parts for a thorough A/C overhaul. And bought some tools.

I picked up an A/C gauge set and vacuum pump today - thought I would hook up the gauges to practice and see how far off it was.

reading around on the subject it seems like I should see (on Lo/Hi gauges)
40/150 static pressure (engine off)
30-35/200 (engine running)

since I get nothing but warm air I wasn't expecting to see these numbers, but what I see is

150+/175 static
150+/250 engine running.

I say 150+ because the needle is pegged against the end-stop

In other words the low side is hugely over-pressured. Not sure what to make of the high side. Seems like instead of a leak, this low-side over-pressure is why it's not cooling. I know I may have over-filled the system playing around with canisters earlier - but don't see how I could have got it to this pressure, could it?

I'm still researching, but what component could cause such over-pressure? I've ordered a compressor, dryer/receiver, expansion valve, R134, PAG oil. Hopefully it's one of those.

-Richard
 
#15 ·
... nothing but warm air
I took the car back to the place that charged the A/C system following the engine rebuild. It blew warm, damp air while it was there and they had no idea what was wrong with it - they offered to purge/re-charge for $125 but i decided I'd find someone with more idea what might be broken.

But then driving to work one hot day last week i flicked the "Auto" switch on for a laugh and...cold air came out! and it's been blowing cold ever since. This is without me changing a single component - I bought new compressor, dryer, expansion valve and refrigerant, but they're all still sitting in their boxes.

I've been reading up on automotive A/C systems but I'm at a loss.
The sequence:
- worked great after re-charge
- then stopped working suddenly
- tried an ill-advised cheapo recharge using a canister with a gauge on it - failure
- while still not working, bought a gauge/manifold set and saw running low-pressure side gauge read very high.
- waited about 6 weeks - car used only a few times
- A/C suddenly started working again.

It seems like the compressor isn't the likely candidate given a) it works now and b) it generated over-pressure? But what would you suspect? Golden rule in my work-world (consumer electronics design) is...if you don't understand why it went wrong, it WILL come back to burn you later. So I know this good state is probably temporary.

Any theories? Thanks in advance.

-Richard
 
#16 ·
Richard, have they checked the expansion valve? They do fail or they get something in them that keeps the refrigerant from expanding It is possible the valve stopped working and then restarted. That is the only thing I can imagine.
 
#17 ·
Richard, have they checked the expansion valve?
Thanks Christopher - no nobody has checked the expansion valve but it seems like the most obvious thing to swap out. While I'm in there might as well change out for the new dryer I got.

I already have a P-flow Condenser - and I swapped the low/high speed fan circuits (brown, brown/white coil wires to relays swapped) and that works. I'll seal up the sides of the condenser, fit and insulate the new dryer - install a heater-hose shutoff. See how that feels.

-Richard
 
#19 ·
Thanks Jason. I think my plan is:
- wait for it to stop working again (inevitable)
- replace dryer/filter, expansion valve - recharge etc.

then see how well that lasts. In the meantime, planning to do the heater block-off valve tomorrow. Definitely noticeable how much better it cools before the car warms up - I'm thinking that's a combination of hot water flowing through the heater, filter/dryer needs better insulation and condenser needs sealing better for efficient airflow.

Thanks for all responses,

-Richard
 
#20 · (Edited)
What if the temp control door inside the HVAC box was stuck,or the stepper motor stalled? That would account for no cold air entering the cabin. He said he hit the AUTO button, and the A/C worked. Maybe his problem is not under the hood, at all.
 
#21 ·
I put the shut off valve in my 91S, but not the LS (yet), as I found that the A/C in the LS is entirely satisfactory without it, even in the hot Southwest. If your system is working as it should I imagine you shouldn't need the valve. It appears to be more difficult to install than in the 91S, less room and shorter hose to the false firewall.
 
#22 ·
I found that the A/C in the LS is entirely satisfactory without it, even in the hot Southwest....appears to be more difficult to install than in the 91S, less room and shorter hose to the false firewall.
Thanks Del, I'll take a look tomorrow and see whether there's enough room to cut the hose - if not I'll try the other things first.

-Richard
 
#25 ·
On our LS, way back when, I inserted a solid foam round seal (backer rod, used for concrete joints) inside the hollow foam seal that sits atop the false firewall. Wanted to ensure that no engine heat got into that space because that's where the HVAC system pulls in outside air.
 
#27 ·
inserted a solid foam round seal (backer rod, used for concrete joints) inside the hollow foam seal that sits atop the false firewall.
That seal does seem like a vulnerable spot, with the rear exhaust manifold just a foot below it. I've got some self-adhesive heatshield fabric I'll attach to the new filter dryer too when that goes in.

I didn't look at the heater hose today because it's about 100degF here. Good day for testing A/C improvements. I'll get some 3/4" hose in case it needs extending - thanks all.

-Richard
 
#26 ·
I always found it was the condensor grill that leaked on mine. It sits in front of the radiator so takes all the stone damage - though saving the radiator in the process.

Has anyone replaced the oil in the aircon pump? Have a spare one and thinking of using a rebuild kit on it but no idea what to do oil wise.
 
#29 ·
frost-switch

Latest on this...

The A/C stopped working again - it was perfect on the way to work, dead on the way home (when it was hot outside..)

Gauges showed normal-looking pressures - but compressor wasn't cycling. Fuses were all good - so pulled the trinary-switch's red-connector next to the dryer and shorted it together, still no compressor.

Then i saw on the schematic that the frost switch was in series with the signal that eventually grounds the compressor relay. Pulled the wires off it and measured open-circuit. I shorted the frost-switch wires together and now the compressor was cycling - cold air blowing once again.

That switch failure could be intermittent and related to the previous failures, but could also be a fresh, new failure which is what I suspect.

As far as I understand the frost-switch function..I live somewhere it gets below 40F about twice/year, and I won't have the A/C on those days - I think I can live without a functional frost-switch can't I?

Cheers,

-Richard
 
#30 ·
Hello all,

A/C is still working as described above. I should note that I described the A/C compressor as "cycling" - when in fact it just successfully turned on - and stayed on. I've read that this is how the USA system works and mine is doing that.

I have another A/C question though - i'm building another engine (for a Lancia Stratos replica kit) - it's a 1995 24v engine with a very tired looking A/C compressor. So I bought a new one, a Sanden SD7H15 - their compressor part #4653
4653 Compressor

That was the closest I could find to the original part number - certainly the compressor body is correct and mounts to Alfa support brackets in the correct place/orientation. However the pulley is completely wrong - too few grooves, wrong diameter etc.

No problem, switch the pulley from the old compressor onto the new one. But the new compressor's front clutch plate won't work with the old pulley - just wrong diameter/depth etc. So use the old clutch - but..2 problems there.
1) the old clutch plate is broken, the joints where the moving plates pivot have separated - not repairable as far as I can tell.
2) the shaft on the new compressor has different dimensions - so the old shimming of the gap between clutch and pulley no longer works. Tighten the front nut and the whole thing is jammed together.

So I need
a) a new clutch plate - does anybody know if Sanden supplies that as a separate part - Sanden website isn't much help
b) new shims - is that feasible? to find new shims that fit over the new compressor's keyed shaft to re-set the air-gap?

Thanks for any leads/suggestions.

-Richard
 
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