I have cleaned the control head - the AC blows cold when it works -- the programmer works when the control head tells it to: Any help and questions are sure enough welcome! I have been fighting the AC/Heater climate control. When it does not work the control head has all dashes. I got it to work by cutting The brown 50 wire supplying a direct source of p0wer to the head but when I put the power just to the head from the battery the car will not crank over. I noticed when when I start the car there is a momentary loss of power to the control head so I was thinking that I would just give it another power source which works if the original power is reconnected and the jumper from the battery is attached to that junction (brown wire cut in two but bare) as fast as I can the AC will work. If I do not get it to the junction in time I get all the dashes again. It works every time if I am fast enough to put the 12VDC+ to the brown #50 junction. I hope I have explained this clearly enough. The weird thing is I can up plug the control head and the car will start. Cut #50 brown wire everything in the car seems to work but will not start. I have looked at the schematics for the starter circuts and there is no reference of #50 brn wire to the starter enable relay or starter solinoid circuts.

 

The problem is the programmer. There is a filter capacitor that gets real weak and the 5 vdc logic line goes low and cause the chips and transistors not to work and have the problem you have. Usually 4 capacitors are replaced which takes care of future problems. Fixed several of them for this exact problem.
So you can get another programmer, or fix the one you have. If you can solder and work on a printed board, put the time in then you can repair it.

Here is the link for the information.Since you car is a 91,it might be slightly different, not sure
https://www.corvetteforum.com/forums...-repaired.html

 

wow! thank you so much. I will pull it out get the caps and get them replaced!!!

 

I got the programmer out and the PCB connector is white and has corroded pins. I have been cleaning with a fine emory board compliment of my wife, some q-tips and alcohol. 90% of the problems have dissappeared. I am definately on the right track. I have the capacitors on order for 12 bucks! 100 Uf @ 35vdc and 3 22 Uf @ 25vdc I went ahead and got a new soldering iron and "helping hands" PCB holder. So when all this stuff gets here wednesday I will change the caps. I did not get a solder sucker those can be quite handy I think I will order one of those too, did you use one?

 

Because I worked in electronics I have been using a solder sucker for many decades. I also use a heated de-soldering vacuum tool which does a better job.
The car is 90s technology and there is lots of space between parts and a sucker will be fine. If your doing more current high tech work de-soldering tools are the only way to go.

 

Went out this morning 57 degrees, programmer is hooked up but laying on the floor. AC did the same thing after cleaning real good. The only difference was the temperature. I took a heat gun heated the programmer boards up and wa la the AC worked perfectly wich points to the capacitors on the board I am going to replace. I know they break down over time and they are sensitive to heat. Do you agree?

 

It's also possible the heat is making a weak solder connection (cold joint) make a connection.

 

Great thought. Thanks

 

definately the programmer. I have parts on order. I also have contacted Batee.com and they can rebuild my unit for $125.00 add $100.00 if the PCB plug needs to be replaced. When putting the programmer back in I have a #8 nylon screw spacer cut to fit over the 13mm deep vacuum hose block so I can put a 7mm socket on the nut and just spin it off. Saves a lot of time better than chevrolets idea of a press nut. Put in a threaded bolt long enough to reach with a socket.

 

Well....you already ordered a programmer? But, there's a vid on Youtube how to rebuild/repair them. I haven't watched it....Just noticed it this summer. I have no idea how extensive the video is. I'm fairly sure it was posted by Batee.

 

No, I have orderd the capacitors to repair my existing programmer. I have verified (as best I can) that the capacitors are bad. I plug the programmer in take a heat gun with a nozzle on it that allows me to concentrate the heat in one area and the programmer works. I have to separate the two PC boards to do this but it works every time. The parts arrive today -- I will install and see how it goes and will repoart back.

 

Your going to be fine. The hardest thing is getting the programmer in and out of the car. The replacement of the caps are relativity easy, just to be careful of any solder blobs and cleaning off with alcohol lightly.

When I posted my repair back in 2014, I never heard of Batee and was doing my own thing. I think we had parallel efforts I was unaware of. Since then he sure has grown to doing lots more things. I have talked to them many times and ordered the film overlay for the speedometer myself. He gives good tech support and helpful all around.

 

The programmer was not as hard to remove and others have said. I am 5 foot 7 and weigh about 155 I just took out the seat and laid on my back. The suction hose boot is a pain but I will use a nylon extention and nut to put back in so the next time I can use a 7mm nut driver to take off. Are the capacitors polarity sensitive when soldering back in?

 

All capacitors are marked + and - on the old and new ones. Usually only one marking is on the capacitor.
There may be markings on the board as well top or bottom but don't count on it. Draw a picture, take a picture, write it down as the old caps come out. Polarity does matter a lot, get it right.

 

You have been very helpful. Thank you. I replaced the caps but they were 1/2 the phisical size. The ratings were all the same worked for about a minute and quit. Sent unit out today to Batee. I need better soldering equipment I think i had a cold solder joint.

 

I wonder if anyone has built a manual ac control package for these cars or adapted a control package from another car to work. Seems to me all you would need is a five valve manifold something like this only with better panel mount valves
and then get a potentiometer to supply a variable voltage to the blower control module to regulate fan speed and a toggle switch for the AC compressor. The probrammer and the control head could be removed and the cars ac would work manually. It would not be a streatch to incorporate a digital thermometer to control the AC compressor with a pretty good dead band so the compressor does not cycle and also to control the fan automatically I think the out put needs to be like 2 to 7 volts to the blower control module (fan resistor some call it). These parts for our C4s are not made anymore and are not very reliable.