possible to wire a/c with just a toggle switch?
Thread Starter
Drifting
Joined: Dec 2007
Posts: 1,672
Likes: 8
From: Sumter South Carolina
possible to wire a/c with just a toggle switch?
My a/c climate control has been on the fritz for a few months now and now wont turn on the compressor or fan (was working after i put new fan control and fan but now nothing). The thing does this light desplay and blinks and all the lights look like a christmas display.
Im wondering can i just remove the thing and put 3 switches, cold, hot, and defrost... just make them 100% or off. Would make it a lot simpler. And would save on weight, give me a place to mount other switches and less of a headache.
Im guessing there are a lot of resistor values but i just want a switch that changes the air path to cold, switches the compressor on, and turns the fan to 100%.
Im not paying $300 to get a new unit and hope that fixes the problem. Already spent enough time piddling on it.
Im wondering can i just remove the thing and put 3 switches, cold, hot, and defrost... just make them 100% or off. Would make it a lot simpler. And would save on weight, give me a place to mount other switches and less of a headache.
Im guessing there are a lot of resistor values but i just want a switch that changes the air path to cold, switches the compressor on, and turns the fan to 100%.
Im not paying $300 to get a new unit and hope that fixes the problem. Already spent enough time piddling on it.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Nope.
The electronic a/c control head is only one portion of a multiple component system that seeks permissions and info from the other pieces...
you still have the a/c programmer and would loose ALL vent control plus you loose hot/cold air blend control.
You would loose auto-cooling fan control.
Your problem is simple. Get the control head rebuilt. There are only 2 things that ever fail in this very reliable system...
1. the BCM (blower control module) if the fan goes crazy or the clutch won;t engage
2. the control head. (if suddenly displays in Klingon)
Often the control head just needs to be taken apart and the contacts on the 2 boards need to be cleaned and the slot tightened for solid contact.
Rebuilt control heads run $75 to $150. Used are available all over flea-bay.
The electronic a/c control head is only one portion of a multiple component system that seeks permissions and info from the other pieces...
you still have the a/c programmer and would loose ALL vent control plus you loose hot/cold air blend control.
You would loose auto-cooling fan control.
Your problem is simple. Get the control head rebuilt. There are only 2 things that ever fail in this very reliable system...
1. the BCM (blower control module) if the fan goes crazy or the clutch won;t engage
2. the control head. (if suddenly displays in Klingon)
Often the control head just needs to be taken apart and the contacts on the 2 boards need to be cleaned and the slot tightened for solid contact.
Rebuilt control heads run $75 to $150. Used are available all over flea-bay.
Le Mans Master
Joined: Aug 2005
Posts: 7,392
Likes: 218
From: Merritt Island, FL
Nope.
The electronic a/c control head is only one portion of a multiple component system that seeks permissions and info from the other pieces...
you still have the a/c programmer and would loose ALL vent control plus you loose hot/cold air blend control.
You would loose auto-cooling fan control.
Your problem is simple. Get the control head rebuilt. There are only 2 things that ever fail in this very reliable system...
1. the BCM (blower control module) if the fan goes crazy or the clutch won;t engage
2. the control head. (if suddenly displays in Klingon)
Often the control head just needs to be taken apart and the contacts on the 2 boards need to be cleaned and the slot tightened for solid contact.
Rebuilt control heads run $75 to $150. Used are available all over flea-bay.
The electronic a/c control head is only one portion of a multiple component system that seeks permissions and info from the other pieces...
you still have the a/c programmer and would loose ALL vent control plus you loose hot/cold air blend control.
You would loose auto-cooling fan control.
Your problem is simple. Get the control head rebuilt. There are only 2 things that ever fail in this very reliable system...
1. the BCM (blower control module) if the fan goes crazy or the clutch won;t engage
2. the control head. (if suddenly displays in Klingon)
Often the control head just needs to be taken apart and the contacts on the 2 boards need to be cleaned and the slot tightened for solid contact.
Rebuilt control heads run $75 to $150. Used are available all over flea-bay.
Good advice. No reason to mickey-mouse your way around this, unless you just don't want any HVAC at all.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Before I pulled out any boxes, I would try to fix it and gather more data. If on the 89 you can pull the codes, I would do that first. I would also disconnect the battery and give everything a reset. Some things might or might not clear up but at least the indications might be more believable.
I would also get an indication of if you are low on Freon. I would check the static pressure and first see what that is. I might also manually run 12 volts to the compressor and get it turned on and continue to check the pressures. You would have a more complete picture of the Freon and problem.
After that if not progress is made, all previous is good.
I would also get an indication of if you are low on Freon. I would check the static pressure and first see what that is. I might also manually run 12 volts to the compressor and get it turned on and continue to check the pressures. You would have a more complete picture of the Freon and problem.
After that if not progress is made, all previous is good.
Last edited by pcolt94; Apr 27, 2012 at 10:46 AM.
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
When I had problems with the 90 & did not have time to mess with it I used a toggle to turn on the compressor. 12V before the low pressure switch.
If the radiator cooling fans are not running: on a 90 the fan relay ground wires need a switch to ground to turn them on manually..
Now that I'm thinking about your problem I have some spare AC parts for an 89 that I collected when I had one many years ago. Will look for them after lunch.
Have a used 88-89 programmer group 9.275 (C68) 16069591 if you need one.
If the radiator cooling fans are not running: on a 90 the fan relay ground wires need a switch to ground to turn them on manually..
Now that I'm thinking about your problem I have some spare AC parts for an 89 that I collected when I had one many years ago. Will look for them after lunch.
Have a used 88-89 programmer group 9.275 (C68) 16069591 if you need one.
Last edited by Churchkey; Apr 27, 2012 at 01:50 PM.
Thread Starter
Drifting
Joined: Dec 2007
Posts: 1,672
Likes: 8
From: Sumter South Carolina
Well here is the story, i replaced the blower control module w/ ac delco, then i replaced the blower since i was told to do both.
Then it was working about 90% if the control in the cab wasnt on the fritz. Then i changed my intake to a high flow manifold and it was during the winter and i didnt use the ac for a long time then one day went to turn it on and it didnt do anything.
Then about every day or two the thing flashes all the lights in varying order like a demo on a stereo and the number display never looks right until i press the off button like 10 times and then it will go back to read 75. But no controls will respond. The light will come on saying that i have chosen say ie defrost but no compressor or fan comes on.
I just have other stuff i want to spend time on other than figuring it out, i guess ill try manually testing the compressor.
Then it was working about 90% if the control in the cab wasnt on the fritz. Then i changed my intake to a high flow manifold and it was during the winter and i didnt use the ac for a long time then one day went to turn it on and it didnt do anything.
Then about every day or two the thing flashes all the lights in varying order like a demo on a stereo and the number display never looks right until i press the off button like 10 times and then it will go back to read 75. But no controls will respond. The light will come on saying that i have chosen say ie defrost but no compressor or fan comes on.
I just have other stuff i want to spend time on other than figuring it out, i guess ill try manually testing the compressor.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
My exact thought was not to test the compressor, because with the problems you have indicated other problems. The compressor is probably OK. I just wanted to run the compressor to ascertain if Freon was low causing a sensor the feed back to the control head, ECM or programmer causing a fault and the indications you have. Just wanted to be clear.
