Guest Silverghost Posted February 23, 2007 Share Posted February 23, 2007 I have a 1991 Chevrolet 454SS Truck with an Electronic Heat/AC control system.The Problem: My control now stays active and the compressor clutch stays on with the Ignition key switch off;so does the fan blower motor! This runs the vehicle battery down in very short order.If the AC and Heater fuse are removed the control still stays active and the AC clutch still stays energized, as does the fan blower motor!In fact with the AC running the AC compressor clutch does not cycle like it should...It stays on all the time! Any idea what can be done to fix this problem?The AC/Heat control is no longer available from the Chevy dealer...I do not think that the Standard Silverado truck used this same Electronic control...I cannot find a replacment.Does anyone fix these electronic controls?Could there be a short in the wiring somewhere that is causing this problem?Any and all help greatly appreciated! Link to comment Share on other sites More sharing options...
Oldsfan Posted February 28, 2007 Share Posted February 28, 2007 The GM parts catalog says that all '91 to '94 C/K pickups with a/c use the same control head, part #15169225, still available from GM for $201.92. Plenty of stock available.Paul Link to comment Share on other sites More sharing options...
Guest Silverghost Posted March 2, 2007 Share Posted March 2, 2007 Thanks Paul! I placed one on order today!I hope it cures my problem...? Link to comment Share on other sites More sharing options...
Guest Silverghost Posted March 2, 2007 Share Posted March 2, 2007 Problem UPDATE: Looks like I have a real electrical problem still with this Heat/AC on this 91 Chevy 454 SS Truck... Installed a NEW Delco Heat/AC control center today...The problems are still here... AC clutch on all the time...24 hours/day Ignition key off...Clutch still engauged...AC/Heat Blower still running... Fuse removed for AC/Heat...Clutch still engaugedBlower still runs...with IGNITION OFF!!!Removed control center & left connector hanging empty + fuse out + Key off... Clutch STILL ENGAUGED & Blower STILL RUNNING!Where is this Power comming from??? 12.4 Volts!There must be some sort of short to 12 volt power or ground in the wiring harness ...But which harness?Under Dash? OR Under-hood Engine bay?How can these items be still runninng with Control Removed, AC/HEAT Fuse out, & Ign. Key OFF!I am forced to remove the + battery cable to stop this drain or battery will run into the ground fast!!!Any and all help Greatly Appreciated!!!I am Stumped !!! Link to comment Share on other sites More sharing options...
Oldsfan Posted March 2, 2007 Share Posted March 2, 2007 You must have a short, or backfeeding, somewhere. Have you pulled the connector off the compressor? That'll keep the compressor from running. It'll be interesting to see what that does with your blower motor. Definitely shouldn't be running with the fuse out. Are you sure you have the right fuse pulled? Next step would be to start pulling fuses and see what makes it (them) stop.Paul Link to comment Share on other sites More sharing options...
Guest Silverghost Posted March 3, 2007 Share Posted March 3, 2007 Paul: I did remove ALL the fuses and thermal breakers...The A/C clutch still stays engauged...the fan blower motor still runs & the AC/Heat controller display stays lit ! All this with no fuses at all and the Ign Key off and out. I do remove the compressor clutch connector to run the truck...the blower still stays active! I cannot understand where the 12.4 Volt power is comming from with all fuses removed...This is the strangest electrical glitch I have ever seen in my life...I am at a complete loss as to why or how this is happening! Link to comment Share on other sites More sharing options...
Guest Silverghost Posted March 4, 2007 Share Posted March 4, 2007 Hello: Does anyone know what role the truck's ECM computer has with the AC/Heat-blower system? Could a faulty ECM computer be causing my AC/Heat-Blower electrical problems? Link to comment Share on other sites More sharing options...
Oldsfan Posted March 5, 2007 Share Posted March 5, 2007 I'm not a technician, just a parts guy, so you have to take all of this with a grain of salt.I doubt the ECM has anything to do with fan blower speed. BCM, maybe, and I haven't looked to see if this uses one.ECM might be related to the compressor. Something has to tell the compressor to kick off under full throttle. Used to be a cut-out switch associated with accelerator linkage, but later cars started using throttle position sensorS with the ECM cutting off the compressor. Could the ECM be that screwed up that it would run the compressor constantly? Dunno.Paul Link to comment Share on other sites More sharing options...
Guest Silverghost Posted March 10, 2007 Share Posted March 10, 2007 Problem Update: Today we removed both ECM Computer connectors & also the three AC Blower relays which should take these items out of the picture... Result: When the 12Volt Truck battery is re-conneted the AC Compressor clutch energizes all the time! No Change! The problem Remains! What do I check now??? I am REALLY STUMPED ! Could this be a short in the Engine Bay Wiring Harness? What else could be causing this??? Link to comment Share on other sites More sharing options...
GMPARTSMAN Posted March 11, 2007 Share Posted March 11, 2007 Possibly one of the relays contacts are permanantly closed due to arcing and fusing of the contact points.Switch them around with others if the part numbers on the cases are the same. Link to comment Share on other sites More sharing options...
Guest Silverghost Posted March 11, 2007 Share Posted March 11, 2007 It can't be a relay causing this as I have remvoed them all in an effort to troubleshoot this problem. All AC/Heat controls, fuses, ECM Computer, relays have been removed; and their sockets left empty...still the clutch energizes as soon as I connect the Truck's 12Volt battery... I must now un-plug the compresor clutch coil or unplug the pressure cycleing switch on the receiver-dryer to drive the truck. When parked I must remove the + battery cable...or the battery will run into the ground in very short order. Very Very Strange Indeed ! Link to comment Share on other sites More sharing options...
Guest exnitro Posted November 18, 2011 Share Posted November 18, 2011 I have a 92 Riv doing the same thing. Did you ever get the problem solved? Can you give me a hint? ThanksJim:confused: Link to comment Share on other sites More sharing options...
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