1995 164Q air conditioning - Alfa Romeo Bulletin Board & Forums
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post #1 of 14 (permalink) Old 05-29-2019, 08:22 PM Thread Starter
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1995 164Q air conditioning

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

Last edited by GTV67; 05-29-2019 at 08:31 PM.
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post #2 of 14 (permalink) Old 05-29-2019, 08:56 PM
Del
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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.

Del

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1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6

Last edited by Del; 05-29-2019 at 09:14 PM.
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post #3 of 14 (permalink) Old 05-30-2019, 05:57 PM
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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.

Ciao, Alfisto Steve
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post #4 of 14 (permalink) Old 05-30-2019, 08:15 PM Thread Starter
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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
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post #5 of 14 (permalink) Old 06-15-2019, 10:49 PM Thread Starter
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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
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post #6 of 14 (permalink) Old 06-16-2019, 02:42 AM
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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

Ciao, Alfisto Steve
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post #7 of 14 (permalink) Old 06-16-2019, 07:08 AM
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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.
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post #8 of 14 (permalink) Old 06-16-2019, 08:03 AM
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I have to agree with John.

Take it to a good A/C shop. If the seal on the compressor is bad, you could rebuild or I have new compressors.

Also check the POA valve Schrader valve, I have seen those leak too. But it could be anything and you don't want to cause more harm.


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post #9 of 14 (permalink) Old 06-16-2019, 12:55 PM Thread Starter
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Quote:
Originally Posted by Alfisto Steve View Post
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
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post #10 of 14 (permalink) Old 06-16-2019, 01:38 PM
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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.

Ciao, Alfisto Steve
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Alfa Semi-Daily driver: USA model - BB2 1991 164S Black Beauty II ALFISTO [U]

[U] BB1 1991 164L w/S engine and A/T now excess to inventory [U]

Daily driver and parts hauler but not car hauler 2004 Jeep Grand Cherokee Overland 4.7L H.O. V-8

"A day without an Alfa whine is like a day without sunshine"

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post #11 of 14 (permalink) Old 06-16-2019, 04:53 PM
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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.

Christopher

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post #12 of 14 (permalink) Old 06-16-2019, 06:45 PM
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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 redneck ugly, but would probably work.

https://www.alfabb.com/bb/forums/164...ion-guide.html

https://nostalgicac.com/16-x-22-supe...condenser.html

John Stewart
74 Spider
91 164S

Last edited by Roadtrip; 06-16-2019 at 06:57 PM.
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post #13 of 14 (permalink) Old 06-16-2019, 08:41 PM Thread Starter
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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
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post #14 of 14 (permalink) Old 07-01-2019, 08:19 PM Thread Starter
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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
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