AC blows warm air in city driving

[abair]

The Air Conditioner in my 1994 5 speed with Auto HVAC keeps the car very comfortable with nice cool air right after starting a trip or at highway speeds. In hot weather it will stop working and start blowing warm air when I am stuck in slow traffic or seemingly any time it gets hot under the hood. I have seen the compressor pulley NOT turn when the AC is on yet there is warm air blowing inside. Does this mean the compressor is bad or needs to be "reshimmed" (as described on SHOtimes.com)? Or is there a reasonable possibility the Constant Control Relay Module (CCRM) is telling it to disengage (like it does at wide open throttle) because of a sensor reading? Any help would be appreciated. Thanks, Adam.

 

[naval-avi8or]

Just had the same problem on my 94. I troubleshot mine and I can give you a quick test for you to try. Take a 2-3' piece 1" pvc pipe or a broom handle(or anything simular). When the ac quits cooling turn it on max and pop the hood. Use the tapping device (ie broom handle) and tap(may have to wack it pretty good) the compressor clutch several times as needed, if it engages then its time for a new clutch and coil. You can reshim it but why do all that work to just have do do it again shortly down the road. If the clutch has worn down and the airgap is to large then the clutch itself is worn out. I bought my clutch and coil at autozone for 89 bucks NAPA has it for the same price but with a 1 year warranty rather than autozones 3 month.

<small>[ July 20, 2002, 07:17 PM: Message edited by: naval-avi8or ]</small>

 

[sdpatt]

First check the refrigerant pressure. If the pressure is too low, the cycling switch on the acculmulator will prevent the compressor clutch from engaging to protect the compressor. The high/low pressures onthe R134a system should be about 250psig/50psig. Second, check to see if the radiator fan is running with the climate control set to AUTO or MAX A/C (or anything but VENT or FLOOR). If the fan is not running, check for 12V at the power connector. If the power is there, the motor's brushes have probably worn out. You can replace the brushes (hard to find), the motor (check RockAuto.com and others) or the entire fan and shroud assembly from Ford.

 

[cetris]

I am the original owner of a 40K mile '92 SHO that is doing the same thing. It works fine (delivering 40 degree F air on a 90+ degree day) when I first start it up, but after 15 - 30 minutes of service, the compressor shuts down. I removed the connection from the cycling (pressure?) switch (right next to and below the battery, near the front of the vehicle) and jumpered it out and ran the car a while like that, and it still did the same thing. I am inclined to believe that the switch isn't the problem, at least in my case. I haven't tried whacking it with a stick yet....I guess it doesn't cost much to try it. Oh yea, my radiator fan runs OK, I think. Isn't there a temperature switch somewhere too that is suppose to cycle the compressor to keep it from getting to cold and freezing either the evaporator or the condensor up?

I will let you know if/when I get it figured out.

Chuck- Charlotte, NC

 

[whlav]

Had the same symptoms on my 94ATX. Finally(hopefully)got it fixed. Needed new clutch and cycling switch. Running fine so far. Good luck.

 

[abair]

Thanks for all of your input.
1. Does the Cycling/Pressure switch connection to the refrigerant line have a schrader valve on it so the switch can be removed w/o losing refrigerant? Can this switch be bought at an AutoZone, etc.?
2. Does anyone have recommendations for removing the clutch from the compressor? It looks like the battery and tray should be removed and I am sure the pulley nut is wicked hard to remove. Can the AC clutch be bought at an AutoZone, etc.?
Thanks, Adam

 

[sdpatt]

abair,

1) Yes and yes.

2) You can check that the clutch is getting power by checking the voltage at the electrical connector on the forward (to the front of car)face of the electromagnet or at the integrated control module above the radiator if you have a wiring schematic.

Scott

 

[naval-avi8or]

To remove the clutch you will have to remove the Battery and tray, accesory belt, two idler pullies, alternator, and unbolt the comperssor (without disconnecting the lines). Then you will have to rotate the compressor up to access the pully with the pully puller. As far as the nut it was the easiest thing on the a/c compressor to remove. Autozone will loan the spanner wrench to hold the a/c pully. You will need both inner and outer snap ring tools.

 

[cetris]

naval-avi8tor,

Wow, I thought removing the clutch was suppose to be an easy task?! Below is a copy/paste of a procedure I got from the shoclub.com board. It sounds easy enough, but it sounds like he is just gently prying the clutch off with a screwdriver after removing the center nut holding it onto the compressor. Again, this is copied from the shoclub.com board, under "care and feeding of the Taurus SHO". I have never done this (yet), so maybe I am missing something here??

Chuck- Charlotte, NC

*************QUOTE FROM SHOCLUB.COM********

Make sure it's the clutch that is not turning on (engaging). Watch the A/C compressor (have the AWA turn the A/C Max on and off to see the clutch in action). With mine, the A/C quits after 15 minutes and the clutch disengages and does not re-engage. If you tap (I used a broom handle) it and it re-engages, then the air gap needs adjustment.

You can also check the clutch gap (relatively easy, at most, only need to remove the battery to get to it). If the gap is too large, take out a shim (if you have a caliper, measure the shims and figure out what one to take out to put you in print). Check the gap (do NOT be outside .021 - .036) after re-assembling the hub. If you cannot remove enough shims to get the proper gap, you can buy just the hub (which I believe comes with more shims) as long as your coil is not toasted. The local Ford dealer quoted me about $45, but I didn't need it (yet).

Everyone tells me that this may not last and that the clutch is probably bad, but at least one SHO owner said his lasted 4 years after the reshimming.

Steps:

1 - Remove the battery

2 - Remove the battery tray

3 - Remove the 12mm bolt holding the A/C clutch on. This is a little tricky because you need to keep the clutch from turning to loosen the nut. I used an angle screwdriver wedged against the fender body.

4 - Don't lose the lock washer.

5 - Remove the clutch. Use two big screwdrivers, and wedge it out. Don't bend the clutch. I used a wonder bar (worked very well).

6 - The shims are right in the center. They will fall out. They are ½ washers. I had two, one smaller, one larger in thickness.

7 - I removed the smaller shim.

8 - Re-assemble and watch to see if the clutch stays engaged.

9 - Suck in the cool air.

I could do this in 1/2 hour now. First time, 1 hour.