1995 coupe A/C comp. runs always

[vigman]

Lets review

If you pull the relay ( you never finished the sentence in your post)

The compressor..... does what? ( I hope shuts off )

However some things are NOT making sence..like the LIGHT Blue wire..

That comes from the control head. and is a switched ground
( are you SURE you have 12 volts on it?????)

And if you unplug the sender.. what does the compressor do ( relay in engine running)?

I will scan the schematic for you in the next day or so...


Vig!

 

[jmccloud]

a/c comp runs all the time

It's raining and I've got a fever. Back in a couple of days. Meanwhile, the schematics would be very helpful. Thanks

 

[jmccloud]

Look at this

Found this under the CAC 'Knowledgebase' tab. Wrong year but it looks close. The option C68 must be the electronic control a/c and option C60 the manual control (like mine). Can't wait to get the hood up and measure voltages at the 'Heater and A/C control head' connector B2 (line 259 gry/red). Anyone have an idea where it's located? Also want to check for ground condition in 999 gray lead.
http://corvetteactioncenter.com/kb/question.php?qstId=74

RATS: the wire colors don't match and the '95 high pressure switch has 3 leads. Anyone know where to get this bulletin (or pages of a manual) for a '95?

 

[vigman]

What you NEED

Also.. when you did the Ohm meter test.. you did have the Low side connector OFF right?

 

[vigman]

John I took the liberty of posting you E mail

I believe this information is VERY helpful.

Edited, From John

Your help was very valuable in solving this. Please let me know if you have any suggestions whether and how to post the essence of what follows on the CAC forum.

( This is the way buddy!)

When I followed your instructions to measure resistance from the blue wire and green/yellow wire to ground (low pressure switch disconnected and engine off) I got a few kilo-ohms. When measured disconnected with the engine running, I got a blown VOM. Replacing its fuse, I discovered 12v on the blue wire.

Your schematic suggested that something was really strange, so I decided to take the heater control out and check the blue wire when disconnected at both ends. BIG operation but the wire was just a wire, no connection to ground or 12v.

Since it's so cold, I took the heater control inside the house and took it apart. Lo and behold, even though I have the 'Manual' control (I got out the owners manual and double checked), the heater A/C control had 6 or 7 transisters and a dozen or so diodes doing the logic switching. No rotary switch as shown in the schematic. And the transistor for the A/C has 3.3k ohm bias resisters. Furthermore, that transister had a collector-to-emitter short and was half exploded like a half peeled banana.

A 69cent trip to Radio Shack for a replacement NPN transister and the heaterA/C control works like a charm. No compressor run in OFF VENT or HEAT but it pulls in for the other buttons. I had to heat up the garage a lot to get it to run. Then tried shorting the connector at the low pressure sensor, DUH that was much easier.

So an entire day was spent very profitably. What a booger to get that thing out. But now it's back together and works, thanks to your inputs.


So now we ALL know something new ( I had NO idea that it wasn't a HARD switch)

Thank you for this info!


Vig!

 

[jmccloud]

I believe this information is VERY helpful.

Vig,
Thanks for the nice edit----and the posts.
John

 

[vigman]

Why thank YOU!

See what can happen when you klunk heads together?


Vig!