1990 C68 AC problem
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From: Prince George B.C.
1990 C68 AC problem
Hi all . I had my dash apart to change the heater door control motor and install a heater core. Also while I was there I removed the non-working Delco Bose system and install the correct wiring harness and a JVC head unit as well as replacing all four speakers and amp under the pass. seat. Everything seems to works including my antenna, which didn't before. My AC worked ,compressor cut in, before the dash removal but now it don't ,the compressor don't cut in ,if I back probe the blue wire it will and my pressure gauge indicated that the refrigerant is good. The FSM tell me to hook up a tool that I don't have and look at chart 2 . I was thinking the problem might be a relay or have something to do with the radio install. Any thoughts????
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From: Peoria Arizona.. Resident Gold Cylon
Hi all . I had my dash apart to change the heater door control motor and install a heater core. Also while I was there I removed the non-working Delco Bose system and install the correct wiring harness and a JVC head unit as well as replacing all four speakers and amp under the pass. seat. Everything seems to works including my antenna, which didn't before. My AC worked ,compressor cut in, before the dash removal but now it don't ,the compressor don't cut in ,if I back probe the blue wire it will and my pressure gauge indicated that the refrigerant is good. The FSM tell me to hook up a tool that I don't have and look at chart 2 . I was thinking the problem might be a relay or have something to do with the radio install. Any thoughts????
Does the AC head display Unit Work?, The Blower Etc? Or does the AC just not enguage ? Did you check your fuses? Is the Green LED on the AC Head unit flashing ?
Last edited by Goldcylon; May 20, 2015 at 09:33 AM.
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From: Prince George B.C.
Yes yes and yes . When the temp is turned down the compressor don't cut in. Actually the only way I can get the compressor to cut in is to power up the blue wire. Everything else seems to work good.
Melting Slicks
Joined: Sep 2008
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From: Cherokee National Forest TN
Your problem is caused by the non Bose radio install.
In order for the 90 & maybe up to 93 C68 system to function properly a pair of resistors must be installed with an aftermarket radio.
Will try to find the TSB for you.
Edit: TSB link
On a 90 model the SYS light will not flash the AC will not operate.
http://www.corvetteforum.net/c4/dave8476/index4.shtml
In order for the 90 & maybe up to 93 C68 system to function properly a pair of resistors must be installed with an aftermarket radio.
Will try to find the TSB for you.
Edit: TSB link
On a 90 model the SYS light will not flash the AC will not operate.
http://www.corvetteforum.net/c4/dave8476/index4.shtml
Last edited by Churchkey; May 20, 2015 at 12:08 PM.
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From: Prince George B.C.
I read the TSB on the radio resistor connection. Where do I connect the resistors, at the new radio plug or up under the pass side hush pad. As I have the new wiring harness and I don't think it has the same colour wires that the original wiring harness had. Also when hooking up the new harness not all of the wires are used.
Melting Slicks
Joined: Sep 2008
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From: Cherokee National Forest TN
The lower pic in the TSB link is easier to read ie wire color codes.
@ the loom to the radio head install a resistor in the purple/white wire & the gray/black wire.
A 5 pack of resistors @ Radio Shack cost about 3.00.
Cannot advise about an aftermarket adaptor harness. I used the plug in with wire leads that came with the new radio & spliced it to the Vette loom.
BTW, After installing the resistors disconnect the battery for a minute the C68 system will reset & should then function properly.
@ the loom to the radio head install a resistor in the purple/white wire & the gray/black wire.
A 5 pack of resistors @ Radio Shack cost about 3.00.
Cannot advise about an aftermarket adaptor harness. I used the plug in with wire leads that came with the new radio & spliced it to the Vette loom.
BTW, After installing the resistors disconnect the battery for a minute the C68 system will reset & should then function properly.
Last edited by Churchkey; May 20, 2015 at 02:54 PM.
