Josh Lindauer (76.117.199.101) - Mon Mar 30 14:40:35 2009

I purchased my ’92 Silverado in Dec. 2008. Since I got it the temperature control display has been blinking “A/C” for 2 minutes after starting, than goes away. From the owner’s manual and the GM service manual I realize this means there is a problem in the A/C system. I figured that it was low on refrigerant since the compressor clutch would never kick on, that and that is what it typically has been in the past with other older vehicles. After buying the retrofit 134a kit, I recovered the stuff that was in it, then proceeded to add the new stuff. The pressure kept rising but the clutch never engaged. I looked through the GM service manual and they suggested to do the obvious…Is there power to the wires i.e. the cycling switch and the clutch positive wire. There was not. I inserted a jumper on the cycling wires figuring this would complete the circuit telling me if the switch was bad or not. With jumping the cycling switch I still had nothing, the clutch never engaged. My next thought was well maybe the internal clutch relay or the pump was shot. So I ran a jumper from the positive post of the battery, to the positive post on the clutch relay itself. Then the clutch kicked in, I sucked in the 134a and everything was working. I also did this to the cycling switch, when I added power the clutch engaged and all worked. This tells me I have an electrical issue and the mechanical stuff should work. I don’t believe that it would be the cycling switch because with it jumped it should engage the clutch of the compressor and it did not, In fact it did nothing with a jumper on the cycling wires. I assume that I have an issue elsewhere that is causing a dead spot in the system or else the cycling switch would have power to it. Does anyone have any ideas or faced similar situation or hell even heard of any stories remotely similar to this? I would really appreciate any help, short of taking it to a mechanic who is going to charge me way more than the truck is worth to get this working again. Thanks.

Reply #1 Joe (69.171.162.49) - Thu May 21 00:58:39 2009

Im having the exact problem with my 95 silverado, I have tried the jumping method , and the clutch was not kicking on. Have you found out anything further on this situation?

Reply #2 reagan (208.184.6.23) - Tue Jun 2 12:35:24 2009

must bee a common problem i have it too can jump it and it will freeze you out but if you figure it out let me know i will do the same

Reply #3 reagan (208.184.6.50) - Wed Jun 3 10:21:45 2009

disconnect battery for 10 min let it reset comp. then every thing worked perfect on mine

Reply #4 Lester (64.219.175.34) - Mon Jul 20 12:25:42 2009

Had the same problem on my 1995 silverado. I notice that if the system is low on Freon it the clutch will not cycle on. I put freon in my and clutch started to work. The over situation was that my compressor went out. I finally replaced the compressor and notice if you wiggle the plug that is connected to the pump (next to the low side valve) toward the back of the engine it would cycle on when I touched it.

Reply #5 Joe (52.129.8.50) - Thu Aug 6 11:07:44 2009

I just had this same problem on my son's 92 chev pick up. After trying all the bypasses I pulled the control head out of the dash. I had a used control head and tried it and everything worked fine. The used head did not have the "recirculate" button so I stuck the original one back in and it is now working. I'm not sure if disconnecting the head

reset something or if there is a loose connection. I'm keeping an eye out for another used control head just in case. I'm guessing they are not available from the dealer.

I may have done same result by what "reagan" has posted. By pulling the control head I may have reset the computer. I'll try disconnecting the battery if it happens again.

Reply #6 Tim (70.94.233.177) - Tue Aug 25 01:19:03 2009

The problem is the ac switch on the dash. It is a known problem I just found out. The whole unit has to be replaced. I found one for $550. Ouch. I solved the problem by running a manual switch to the ac clutch. Works fine. Just have to remember to turn off the switch when I shut off the truck. Will run it from an accessory to solve that problem.

Reply #7 vito (24.187.118.32) - Wed Aug 26 20:32:05 2009

in the back of control panel the ground is tripping. there was a recall very hard to find. call grove radiator in neptune nj. fixed in 20min and very cheap

Reply #8 John (67.246.237.128) - Fri Sep 18 17:51:07 2009

I have a 91 Silverado k1500. It has the push button AC and heater control panel. The panel does not function - no fan - no heat - no air - no lights in the panel. The part number label is no longer on the panel but it is the style with the "RECIR" button rather than the "MAX" button (part # 16204785).

I installed a used 16204785 and found the same results. No function - no lights in the panel. I am told the replacement panel was tested aand worked.

There is power showing at some of the connector points on the truck side connector plug.

I have cleaned the connector points on the back of the panel and in the plug connection.

I have checked the fusable links near the fire wall and all seem fine.

I have checked the fuses under the dash and all are fine.

There are three relays behind the glove box. I think one or more have something to do with the AC. I have heard buzzing from these relays in the past but this has gone away. The panel did not work at all before or after the buzzing problem.

Any suggestions?

Thank you

JBB

Reply #9 Marcus (209.106.203.249) - Mon Sep 21 10:06:20 2009

I've got the same problem with my 92 chevy 2wd 1500, and my 90 chevy 4wd 1500. the 92 kinda works, but the blower won't blow on the defrost setting, the 90 won't even show anything on the readout or respond at all. My mechanic says this is a common problem with these early ac/heater digital controller pickups. There's gotta be a cheap, doable solution! Help!

Reply #10 David (64.12.116.198) - Tue Sep 29 12:53:07 2009

Go to E-bay for the A/C Heater control. Pricing is from $10.00 to $660 but the average seems to be around #30.00. Called the dealer for pricing, they want $249.00 but the unit is no longer

available in grey and the black is on backorder. Dealer said he would order in paid in advance plus a $40.00 core charge for the old unit. Didn't know when, or even if he would receive the new unit. Salvage yard is a good option too.

Reply #11 SHORT MAN SINDRUM (76.198.68.185) - Tue Oct 6 21:46:35 2009

i have the same problem... i replaced the control unit with my buddies but still wont work...i am trying to find out where the ac heater control relay is locaded..

Reply #12 smile (222.127.15.250) - Wed Nov 18 22:21:55 2009

Kind of similar with the problem that I saw. The owner just replaced the Freeze plug. It worked for a couple of days but it suddenly stopped again.

• Mr Gasket Freeze Plug

Name:           
E-Mail:         

Optional (please add to our directory first)
Web Link:       
Link Title:     

Message: