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Discussion Starter #1 (Edited)
I've posted about this problem before and I've been trying alot of ideas to fix it. My HVAC appears to work like normal (display lights up, baffles in the ducts move, fan blows) except the a/c compressor will not engage.

The a/c comperssor WILL engage if the the compressor is connected to the battery source. A/C is cold, everything is great except for the fact that the compressor would be on all the time

I've tried 3 HVAC control panels, 3 a/c amplifiers, pressure switches, relays. I took it to a shop, 3 weeks and they couldn't figure it out. They went over the whole wiring. They swore it was the a/c amp, but no luck when i changed it. This was the only shop that would touch my car because of a modified wiring harness (afc, wideband, boost controller, HIDs, nothing that has to do with the a/c).

Here is my idea. Simply add a button that controls an aftermarket relay to manual kick on the compressor. I could even make the button be the A/C button the control panel. I would only use the button when I want to use the A/C.

Does anyone see this as being a problem? Looking at the electrical diagram, I am bypassing a few things like the temperature sensor and pressure switches. I know the compressor is suppose to kick on and off but is it bad to be on for an extended period of time?

I'm out of ideas. I know my solution isn't "ideal" but if it works, it works.

Thanks,
Dennis

 

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506 Posts
I've posted about this problem before and I've been trying alot of ideas to fix it. My HVAC appears to work like normal (display lights up, baffles in the ducts move, fan blows) except the a/c compressor will not engage.

The a/c comperssor WILL engage if the the compressor is connected to the battery source. A/C is cold, everything is great except for the fact that the compressor would be on all the time

I've tried 3 HVAC control panels, 3 a/c amplifiers, pressure switches, relays. I took it to a shop, 3 weeks and they couldn't figure it out. They went over the whole wiring. They swore it was the a/c amp, but no luck when i changed it. This was the only shop that would touch my car because of a modified wiring harness (afc, wideband, boost controller, HIDs, nothing that has to do with the a/c).

Here is my idea. Simply add a button that controls an aftermarket relay to manual kick on the compressor. I could even make the button be the A/C button the control panel. I would only use the button when I want to use the A/C.

Does anyone see this as being a problem? Looking at the electrical diagram, I am bypassing a few things like the temperature sensor and pressure switches. I know the compressor is suppose to kick on and off but is it bad to be on for an extended period of time?

I'm out of ideas. I know my solution isn't "ideal" but if it works, it works.

Thanks,
Dennis


I know it's way off topic, but what do you keep your fuel pressure at?
 

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23 Posts
are your using R134a or R12 and are you using the correct pressure switches? how many lbs of freon is it charged with? ive seen where people put in too small of pressure switch and it wont ever work. and that seems ok i would start checking fuses and ohming out wires.
 

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its not necessarily bad for the compressor to be on all the time, but if it is, then your evap core will freeze up. I think your idea is good and will work but i think it would be easier to fix this prob then to rewire everything for your switch. i know this sounds dumb but have you checked ur cig fuse? also, maybe your thermistor is telling the a/c amp the wrong temp. does ur auto heater work?......this is a very simple wiring diagram and i might be able to help you through it. can u use a DVOM?
 

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Discussion Starter #6
are your using R134a or R12 and are you using the correct pressure switches? how many lbs of freon is it charged with? ive seen where people put in too small of pressure switch and it wont ever work. and that seems ok i would start checking fuses and ohming out wires.
I switched out the pressure sensors with no luck. Then I switched over to a R134 system hoping to fix the problem. The shop filled it with R134a to the correct pressure. They tested the pressure sensors and they ashored me it they are working.

Also, the cig lighter fuse is good and the cig lighter works.
 
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