Like title says. I can get them to work for a day or so by disconnecting the battery for a few min and then hooking it back up. I think its a computer problem. I recently put a new PCM in it but had it programmed by Chevy Dealer. Just looking for any other suggestions before spending a bunch of money on a reprogram or even another PCM. By the way its a 1994 Z28 A4, stock.

 

You already changed the PCM and it didn't fix the problem. No need to do it again. I have never seen a defective OBDI PCM since they came out.

Since the AC won't cool without the fans running, chances are good the entire problem stems from the fans not running.

Time to get Shoes schematic out and start trudging through it.

 

I changed the PCM due to the car dying when it wanted too. I ended up changing the opti and doing a full tune-up at the same time. By the way I wouldn't recommend that job for the average Joe. The back right plug is a pain in the rear.

 

I agree with speedy.

http://shbox.com/1/4th_gen_tech2.html#cooling - courtesy of shoebox

Use this to narrow down why the fans won't come on. Worry about that first.

 

Ok I checked everything I could. I put a jumper on the DLC pins A and B and the fans worked. So I guess its not my PCM. I am not the most patient person not am I the brightest crayon in the box, so schematics drive me bananas. Can someone tell me what else to look at to fix this problem. Pictures help me find things, as well a just a good description.

 

I recently had a problem with my fans and AC not turning on. It turned out that the pcm was not reading the rpm output from the opti. No rpm to the computer means car is not running so no need for fans and AC. I had to buy a new opti cable to fix it.

If your car is running ok with your current opti then this is probably not your problem. But I would scan for rpms and see if the computer is reading properly.

 

If you are saying the fans do not come on with the a/c, then that would be normal if the a/c was not working because of a low charge. The computer locks out a/c compressor operation if the charge is low (and sets a trouble code that does not turn on the check engine light) and therefore the fans are not commanded on. When you disconnect the battery, you clear the a/c code and the a/c and fans operate until it senses the low charge and stops them again. Correct the a/c charge issue and things will operate normally again.

 

I have one of the 24oz cans of r134a with the gauge on it and according to it it is good on freon. I have the real gauges but don't know how to hook them up properly.

 

Shoes point it to test it before you start doing things. Although the cause is likely. It may not be the only reason. Just shoving freon in a system that does not need it can cause more harm than good. And a system that has gone down usually has a leak so it will happen again. If that is the case, after confirming you have a low charge, have the leak fixed. Then evacuated and recharged by a professional.

 

Do have a code 61 for the a/c system present? You'll need a scanner to tell. Even if you have the code, the fans should still work when the ON temp is reached (226°). They just won't work with if the a/c is not coming on (they wouldn't need to).

 

no scanner but I can take to parts store and use theirs. I will also hook gauges up and check a/c pressures.

 

Even if you could find a store that can scan OBD-I, they probably won't be able to read your F body.

Since you don't have a scanner and probably won't find one. Why don't you follow Shoes advice and clear the code and then try the AC like he said?

 

Ok I don't know how to explain this, but I blew a water pump gasket and got a hole in my heater core hose. I replaces the gaskets and repaired the hose. While I was checking for leaks and refilling with coolant the fans and a/c worked like they should. I put the air intake tube back on and they didn't work. I took the air intake off again and they worked. Could this be a problem with my mass air flow censor or something else. There are 2 plugs and a hose attached to the tube and I disconnected the one closest to the intake and nothing. I disconnected the one at the mass air censor and the car dies. Any help would be appreciated.

 

Sounds bizarre. You really need a scanner of your own to aid in working on your car. I don't know how people can work on a modern car without one.

 

Ok took it to my local do it your self shop and no codes were in the system. I did replace my ATC in the intake elbow but that didn't seem to change anything. My next step is too dig out my multimeter and start chasing wires. The only problem with that is I don't know where to start. According to the troubleshooting instructions I followed, if I jump the A and B pins in the diagnostic port then all the sensors, relays, fuses, and PCM are good so what else is in teh system to check.