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95 silverado AC Woes

sst6220 on Fri July 27, 2007 11:10 PM User is offline

Year: 95
Make: chev
Model: silverado
Engine Size: 305
Refrigerant Type: r-134
Ambient Temp: ?
Pressure Low: ?
Pressure High: ?
Country of Origin: United States

Have a 95 chev. silverado. This summer the AC clutch only engages on initial start up by switching to the defrost selector to get the clutch to engage, then switching to AC mode. The AC will work only once this way. When the engine is shut off then restarted the clutch does not engage ,even using the defrost mode. I added 1 can of R-134 thinking the pressure might be low as it has never been charged. No improvement. I should back up a little and say the AC switch inside the truck does not start the cluch either. I did however check for voltage present at the two post plug on the compressor and there wasn't any. I did a quick jumper from the battery to the two posts on the compressor and the clutch will engage. Almost leaning towards the control circut board in the dash. Any comments will be appreciated
Thanks Much

Chick on Sat July 28, 2007 5:20 AM User is offlineView users profile

If the switch inside is working try "jumping" the cycling switch on the accumulator. Or wiggling the plug. Could be a bad switch or connection. should be power to "both" sides of the switch..Also try tapping the front hub inwards, although you say there is no voltage to the compressor?? Try it anyway, since it does work once in a while..If that works, you'll need the clutch gap adjusted..But sounds more like the cycling switch acting up.. Easy to change and cheap enough..
Never add refrigerant without a set of manifold gauges. After you find and fix your electrical problem I suggest having the system evacuated and recharged properly. Only the correct amount of refrigerant should be in the sytstem..hope this helps.
PS: Don't forget to check the compressor relay, sometimes they go bad, switch it with one the same to test...also the connections on the relay sometimes go bad...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Edited: Sat July 28, 2007 at 9:25 AM by Chick

sst6220 on Sat July 28, 2007 6:31 PM User is offline

I unpluged the wires from the accumulator switch, and with the engine running and AC switched in the on max position, I checked the votage on the plug and had voltage on the orange wire, however, no voltage on the green wire. You had acknowledge that both should have voltage on them. I haven't yet tried to jump the switch. I'll try that next. Any other suggestions?
Thanks for the info...

Chick on Sat July 28, 2007 8:04 PM User is offlineView users profile

Jump the orange wire to the green wire on the accumulator switch harness...that "should" start the compressor, if not, let us know..You don't jump the switch, you jump the two wires..Hope this helps.

-------------------------
Chick
Email: Chick

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Freedoms just another word for nothing left to lose

sst6220 on Sun July 29, 2007 10:28 AM User is offline

Well, I just jumpered the orange and green wires from the accumulator switch with the engine running and AC in the run max selection and the compressor clutch did not engage. However being the first time starting the engine in the morning I was once again able to get the clutch to engage by using the defrost mode then switching on the AC button. I did this a couple times. The AC would turn off using the AC switch, however it would not turn it on. I would have to use the defrost mode to engage the clutch. And as I stated before this routine does not work at all when the truck has been driven a while, defrost mode will not engage the clutch. HMMM
Thanks for your time and knowledge.

Chick on Sun July 29, 2007 4:04 PM User is offlineView users profile

with the switch jumped, check for 12 at the clutch coil. If it's threre, try tapping the clutch inwards and see if it grabs..If it does you need the clutch gap adjusted...But it sounds more like the interior control is not working. If no voltage is sent to the cycling switch, then it's the inside switch..Let us know what you find..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

sst6220 on Sun July 29, 2007 5:06 PM User is offline

Just jumped the accumulator switch & started the engine, with the AC set to the on max setting, checked for 12 at the plug on the compressor that engages the clutch.
There is no voltage.

Chick on Sun July 29, 2007 5:11 PM User is offlineView users profile

Check to see if you have 12 at the switch, and change settings until you do. That will tell you which settings work, and which don't Sounds like the selector inside is shot. You may be able to take it apart and clean the contacts, but check for voltage at the accumulator switch first. That will confirm if the control head is sending the signal and voltage

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

sst6220 on Mon July 30, 2007 11:10 PM User is offline

Well, haven't had a chance to do more tests as we are leaving for a little R&R. I'll continue trouble shooting this when I return.
Thanks for your time. I'll let you know what I find.
Thanks

sst6220 on Sun August 26, 2007 12:11 AM User is offline

Well, Haven't had a chance to pursue the AC prob. further. I do have a friend in the auto salvage business. He stated that the 95 silverado climate control panels are sold as soon as they come in and are year specific. This tells me there is an inherent problem with the control unit. He has a look out for me when one shows up in their yard. When I get one I'll let you know if that solves the problem.
Thanks

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