C68 HVAC Problem
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,519
Likes: 3,310
From: Hartford WI
C68 HVAC Problem
Compressor will not come on on it's own. All 3 fuses are checked and good. I checked for codes and no codes with the system diagnostic. Just seems like it never commands the clutch to engage. Monday I will borrow a set of gauges to test but if there is pressure issues, won't the ECM tell me so? That in section 00 there is just 00 tells me there are no error codes.
Anyone have some quick suggestions before I melt from the heat? TIA
What else can I test? Is there a way to command the clutch to come on so I know it can work?
Anyone have some quick suggestions before I melt from the heat? TIA
What else can I test? Is there a way to command the clutch to come on so I know it can work?
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
ECM doesn't store codes for low refrigerant.
However, the AC control does and will display a code and may flash light above button(s). Check FSM for instructions on how to read and how to reset.
Also, the low pressure switch can fail or its connector come off and prevent the compressor from coming on (compressor power runs through this switch). Check near firewall in low pressure line (colder fatter). Check FSM for location and diagnostics.
However, the AC control does and will display a code and may flash light above button(s). Check FSM for instructions on how to read and how to reset.
Also, the low pressure switch can fail or its connector come off and prevent the compressor from coming on (compressor power runs through this switch). Check near firewall in low pressure line (colder fatter). Check FSM for location and diagnostics.
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,519
Likes: 3,310
From: Hartford WI
ECM doesn't store codes for low refrigerant.
However, the AC control does and will display a code and may flash light above button(s). Check FSM for instructions on how to read and how to reset.
Also, the low pressure switch can fail or its connector come off and prevent the compressor from coming on (compressor power runs through this switch). Check near firewall in low pressure line (colder fatter). Check FSM for location and diagnostics.
However, the AC control does and will display a code and may flash light above button(s). Check FSM for instructions on how to read and how to reset.
Also, the low pressure switch can fail or its connector come off and prevent the compressor from coming on (compressor power runs through this switch). Check near firewall in low pressure line (colder fatter). Check FSM for location and diagnostics.
Yes. That is what I am looking at. The light buttons show no flashes. I hit the fan up and down for 5 seconds, got to the diagnostics.. I cycled thru the entire thing and got different readings for sunlight sensor, critical times, etc, etc but when it came to error codes, none. 00 was the error code section and when I pushed the middle button, it should display codes but it just had 00 which, AFAIK, means no codes. No SYS light either.
I have an FSM. Problem is I lent it to someone who is out of town and I don't feel like breaking into his house.
Burning Brakes
Joined: Mar 2010
Posts: 1,094
Likes: 68
From: Providence RI
I went through this problem a couple of times.
Once was a broken ground wire on the compressor connector. I had 12 volts at one terminal of the switch and the compressor would come on if i manually grounded it, but the wire was broken at a butt connector when I extended the harness after installing my super ram which changed the routing of wires.
The second was low pressure. The HVAC controller only gave me the code 9 once or twice. Did you jump the compressor switch with a piece of wire? If you do this, dont do it for long as the refrigerant is what carries the oil through the system. Do you have 12 volts at the compressor connector?
Another test I did was hook my car up to TTS datamaster. It will show you if the ac is being requested or not. Also, if you do get a code, you need to disconnect the battery for a few minutes in order to clear the HVAC programmer trouble codes.
Mike
Once was a broken ground wire on the compressor connector. I had 12 volts at one terminal of the switch and the compressor would come on if i manually grounded it, but the wire was broken at a butt connector when I extended the harness after installing my super ram which changed the routing of wires.
The second was low pressure. The HVAC controller only gave me the code 9 once or twice. Did you jump the compressor switch with a piece of wire? If you do this, dont do it for long as the refrigerant is what carries the oil through the system. Do you have 12 volts at the compressor connector?
Another test I did was hook my car up to TTS datamaster. It will show you if the ac is being requested or not. Also, if you do get a code, you need to disconnect the battery for a few minutes in order to clear the HVAC programmer trouble codes.
Mike
Thread Starter
Team Owner
Joined: Jul 2004
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From: Hartford WI
Grounded the pressure switch, no joy. Checked voltage at reaching compressor terminal, no voltage. At the pressure switch, one terminal was 13 volts and the other was ground.
Burning Brakes
Joined: Mar 2010
Posts: 1,094
Likes: 68
From: Providence RI
You Don't Ground The PressUre Switch,Connect The Terminals Together With A Piece Of Wire And See If The Comp Comes On Or You Have 12V At The Comp. Sorry For My Grammar/Typing...Phones A Db.
Thread Starter
Team Owner
Joined: Jul 2004
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From: Hartford WI
My bad. I mistyped. I mean to say that I connected the terminals together. Compressor doe not come on. No 12 volts at the connection to the compressor when the terminals are connected.
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,519
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From: Hartford WI
OK. I am confused as to which is which. There is a fan and a high pressure switch and there is another nearer to the firewall which I assume is the low pressure switch. Shorted out the low pressure switch and the clutch engages. What gives? If it is short of R134A, why didn't the BCM tell me?
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Burning Brakes
Joined: Mar 2010
Posts: 1,094
Likes: 68
From: Providence RI
Have you hooked up your r134a gauges yet? If theres no pressure, the clutch won't kick on unless you jump it. When you jump it, the controller assumes the pressure is correct, thus no code. When you begin to fill the system, it will suck some of the can in, enough to build some pressure, but then as the system works with low 134a, the pressure drops, trips the switch to turn off the compressor, and sets code 09 on the C68.
The only time I got a 09 code was when i was filling the system with the compressor switch (one on the upper line going into the evap core) and the system wasn't full. I jumped the switch after disconnecting/reconnecting the battery to clear the 09 code, added a few cans, connected the switch, and all was well.
Hope this helps. You need to see if you have a charge in your system. You can push the valve in on the dryer and see if any 134a comes out. If you do have a sufficient charge, your compressor switch might be junk. They sell ones for r12 and r134a so make sure you get the right one.
Mike
The only time I got a 09 code was when i was filling the system with the compressor switch (one on the upper line going into the evap core) and the system wasn't full. I jumped the switch after disconnecting/reconnecting the battery to clear the 09 code, added a few cans, connected the switch, and all was well.
Hope this helps. You need to see if you have a charge in your system. You can push the valve in on the dryer and see if any 134a comes out. If you do have a sufficient charge, your compressor switch might be junk. They sell ones for r12 and r134a so make sure you get the right one.
Mike
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,519
Likes: 3,310
From: Hartford WI
Have you hooked up your r134a gauges yet? If theres no pressure, the clutch won't kick on unless you jump it. When you jump it, the controller assumes the pressure is correct, thus no code. When you begin to fill the system, it will suck some of the can in, enough to build some pressure, but then as the system works with low 134a, the pressure drops, trips the switch to turn off the compressor, and sets code 09 on the C68.
The only time I got a 09 code was when i was filling the system with the compressor switch (one on the upper line going into the evap core) and the system wasn't full. I jumped the switch after disconnecting/reconnecting the battery to clear the 09 code, added a few cans, connected the switch, and all was well.
Hope this helps. You need to see if you have a charge in your system. You can push the valve in on the dryer and see if any 134a comes out. If you do have a sufficient charge, your compressor switch might be junk. They sell ones for r12 and r134a so make sure you get the right one.
Mike
The only time I got a 09 code was when i was filling the system with the compressor switch (one on the upper line going into the evap core) and the system wasn't full. I jumped the switch after disconnecting/reconnecting the battery to clear the 09 code, added a few cans, connected the switch, and all was well.
Hope this helps. You need to see if you have a charge in your system. You can push the valve in on the dryer and see if any 134a comes out. If you do have a sufficient charge, your compressor switch might be junk. They sell ones for r12 and r134a so make sure you get the right one.
Mike
Burning Brakes
Joined: Mar 2010
Posts: 1,094
Likes: 68
From: Providence RI
I don't know the year of your car but Rock Auto has 3 available for my 91...priced from 125-155. Can also buy a pack of ac orings for like 6 or 7 bucks. Also, you can find 5% discount codes online or I have one for you.
I've always had great dealings with rock auto but buying online, there is always a chance that you'll get the wrong part, then its a pain in the butt. You should also check out what's available locally.
Good Luck
Mike
I've always had great dealings with rock auto but buying online, there is always a chance that you'll get the wrong part, then its a pain in the butt. You should also check out what's available locally.
Good Luck
Mike
Race Director
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From: Anaheim CA
Thread Starter
Team Owner
Joined: Jul 2004
Posts: 28,519
Likes: 3,310
From: Hartford WI