[Emilio]

On my 1997 164 TS super my AC acts weird.
When I switch on the airco I feel the compressor kicking in.
But only HOT air is blown in to the car.
BTW my cooling fan is running much more then normal. Since the airco system can also controls this, I assume that that is the cause.
Anyone any idea?

 

[BlackAlfa]

Perhaps your heater flap is not closing and block the air flow through the heater core so the air always get heat up!

Do you have stepper motor or cable control for the heat for '97 TS?

Bob

 

[Emilio]

Thanks for the reply.
I have a 164 Ts from 1997 with climat control.
Today I found out that my system has enough pressure, So, like i though, I can rule out that one.
Indeed, I suspect the steppermotor to be the source of this heat problem.
But another possibility is the interior temp sensor. But, I think, by switching the system to max cooling the sensor is ruled out.

Where is the steppermotor located? And how can I diagnose whether it is faulty?

 

[Emilio]

One small additional question:
With the pre 1994 type replacing the steppermoter is a lot of work.
I understand that they solved this with the facelift type.
Any one any idea on how they made it more simple?

 

[Alfisto Steve]

Changing not made more simple but stepper motor gearboxes were made stronger.

You need to check that rear temp stepper is working (if LHD model visual access is through small door in glove box cavity near release button) and that heater core box lever not broken so door will shut (visual access with hood/bonnet open and looking behind blower motor housing behind false firewall. Looks to see that wire cable attached to an unbroken lever and that it moves when you raise and lower temp on a/c panel.

 

[Emilio]

I guess that it is not strong enough for 350000 km...
What strikes me is that I do not here anything moving when changing the temp settings. No rotten gear noise, no stepper engine noise, nothing.
My car has an airbag at the passenger side, so is that little door still there?
I will check this afetrnoon...
Still hoping for bad connector, but I fear that I will run into dash dismounting.

 

[Alfisto Steve]

Nope not the same your glove box lid is smaller on bottom of dash. But you can still see cable and arm to heater core air door behind false firewall. Remove plastic panel between windshield and false firewall and look down behind blower motor box about where windshield wiper pivot point is and see if arm OK, cable attached and whether it will move when somebody raises and lowers temp buttons on a/c panel with key on.

 

[Emilio]

O.k. I have checked that.
And YES, it moves.
Another good thing to know is that when we put a clamp on the hot water tube to the heater, the air stream in the car gets colder (approx 10 c).
The system it self is also getting reasonable cold.

I do not have a diagram of the system, so I now have no idea where the problem could be.
Maybe the system is over preseured. This would also explain the frequent running of the cooling fan.
Or are there any filters I need to check?

 

[Alfisto Steve]

If the arm moves and it not broken free from air door inside blower motor housing and moves to close door to prevent air flow to heater core sytem should cool down. There isn't any shut off valve to stop engine coolant from circulation through heater core. Coolant always flowing so door has to prevent blower motor air from passing over heater core and into a/c dusts.

Either stepper not shutting door open off entirely or door linkage is broken inside blower motor housing.

The easiest fix is to install a manual shut off valve in hose from engine to heater core right at false firewall. Here is a picture of one installed on a 1995 24v LS (AFM hose etc removed as we are doing a cam timing check on car) off rear of rear head.

On 12v engines the heater supply hose comes off rear of front head.

 

[Emilio]

The linkage feels like the door is good in place and not damage. (if it was damage I should be able to move it by hand.)

If I turn the heater to max heating I can hear the air flow change, and the air is getting more hot.
I have no idea if it can close maximal.

It looks like getting the unit out is not too difficult. But are you sure that my system can not have too much pressure?
(btw, thanks for this great help so far!!)

 

[Alfisto Steve]

By to much pressure do you mean to much Freon pressure in A/C? Not likely, but to little pressure (low Freon charge) will prevent A/C from coming on as compressor clutch will not engage.

 

[Emilio]

Yes, my a/c guy said that too much freon could also cause this. Especially since the cooling fan keeps popping on without having an engine to hot reason.
Too much pressure could also be a reason for swithing on the fan I understood.

 

[Alfisto Steve]

To much freon pressure can only turn on a/c fan if a/c running and freon pressure (normal operation) from heat transfer makes cooling fan relay grounding switch on a/c reciever dryer turn on. This is normal. If a/c system pressure goes really high second pressure saftey side of trinary switch will shut off a/c clutch on compressor.

If a/c system properly charged it will cool car if heater core air door is closed, a/c compressor engages and cooling fan comes on as often as needed to transfer heat out of freon.

 

[Emilio]

So is it wise to ask tmy airco guy to refill it?
I am looking for data on the volume of freon that goes in to the system.
Is there a site where i can find it?

(again many thanks for the answers!

 

[Alfisto Steve]

The 94-95 USA models take R134a 42 oz (2.76lb/ 1.2 kg). Hopefully your A/C tech has equipment to extract and measure how much you now have in car so you know if it is really low. Then he should insert some dye and recharge system and then leak check with a black light. Usually they also add a small amount of R134a compatible PAG Oil too for system lubrication.

If system real low be sure leaks are found and repaired including replacing gauge set attach point valve cores. I usually replace the receiver/dryer 60590126 and attach point o-rings if car still has original one in it, as they become saturated with moisture and system contaminates over the years.

 

[arts164]

Steve... I would like to eliminate the heater as you have shown. I have unplugged the electronics to the stepper motor on my '92L. Blows cool, not cold high seventys. Big deal here in Naples (already). What diameter heater hose are we speaking of, my parts man is asking? Will the stoppage result in less water circulation for engine cooling? Am I being too lazy in not wanting to tackle the stepper? I never use anything but the A/C! Thanks in advance. I enjoy your enthusiasm.

 

[ChazzyD]

If the arm moves and it not broken free from air door inside blower motor housing and moves to close door to prevent air flow to heater core sytem should cool down. There isn't any shut off valve to stop engine coolant from circulation through heater core. Coolant always flowing so door has to prevent blower motor air from passing over heater core and into a/c dusts.

Either stepper not shutting door open off entirely or door linkage is broken inside blower motor housing.

The easiest fix is to install a manual shut off valve in hose from engine to heater core right at false firewall. Here is a picture of one installed on a 1995 24v LS (AFM hose etc removed as we are doing a cam timing check on car).

Went off to O'Reilly's today and asked for one of these. Here it is: Murray #84707 Shut-Off Valve for 3/4" heater hose just like in Steve's pic, On the Shelf! $9.49. Go and get you one! Mine is in and we will see if my heat-soak problems are over! Alfabill seems to be offline so I went hunting and it paid off.
Charles
'91 164L 5 speed

 

[BlackAlfa]

Here's what I have in our green '91L:

 

[ChazzyD]

Now that's an interesting config. but how do you determine what valve to open and which one to close and for what purpose? The one going to the core I understand because that is what I did today but what is the other valve for? The tee going to the tank line makes sense because the coolant would than flow to the rad return line.... OK, I get it, when you close the line to the core, you open the line to the return line to keep coolant flowing. When you open the line to the heater core, you close the line to the crossover and it works like the stock config. Brilliant! Do you really need the crossover though? Most stock configs have a heater valve that closes automatically (with the climate controls) and does no harm, but do they normally divert coolant to return as your config does, or just shutoff the line to the core? Wish Alfa had gotten this one right to begin with, really one of the most REALLY unexcusable things on the car, IMHO. And yes my flapper (stepper motor) is working, I checked. Thanks for the pic. Just went to get some gas and nice cool air flowing through the vents (A/C not working right now so I REALLY needed ambient air and not heated air, next project) :rolleyes
P.S.-Went to replace the hose from the bottom of the coolant tank to the rad pipe, well, it is not 3/4" hose like the (to) heater core line - something a little bit bigger, uff da!
Charles
'91 164L 5 speed
Chattanooga, TN

 

[BlackAlfa]

OK, I get it, when you close the line to the core, you open the line to the return line to keep coolant flowing. When you open the line to the heater core, you close the line to the crossover and it works like the stock config.

Yup, you got it. When the heater core line is shutoff, I can choose whether to shutoff the crossover line.

Do you really need the crossover though?

No, I think things should be OK with just a shutoff (as in Steve's) and without the crossover (bypass). With a shutoff valve only, the coolant need to do a U-turn (force by the water pump, go through the engine's internal passages and return to the thermostat area before diverting to the radiator). This is OK as long as there's enough flow to the flywheel side of the engine (and I think there is). This config probably allows a slightly faster cold start engine warm up too (since the coolant just circulate within the engine). With the bypass, one advantage is that it allows an additional path to move coolant in hot days.