A/C Troubleshooting
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Joined: Nov 1999
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From: belton texas
A/C Troubleshooting
Have a 90 which blows fuse as soon as you press button to turn on. The car had been sitting for 3 to 4 months. I didn't ever turn the system on to let the A/C run during this period. Best of my knowledge the system worked fine before this idle period. I also had the system converted to 134 about a year ago and had replaced the compressor and clutch at that time.
My Son is getting married this weekend and I really need to solve this problem by the end of the day tomorrow if I can. He wants to drive away from the wedding in his 90 and it is July in TEXAS!!!!!!!!!!!
Wiring harnesses are unmolested trunks so nobody has rigged things. Real original setup. Any suggestions on a methodical procedure to work my way through this. Think I got continuity at the clutch female connector side and also continuity at the clutch connector male side (not running/ign off)? Have multimeter in hand! Thanx Bill :party:
My Son is getting married this weekend and I really need to solve this problem by the end of the day tomorrow if I can. He wants to drive away from the wedding in his 90 and it is July in TEXAS!!!!!!!!!!!
Wiring harnesses are unmolested trunks so nobody has rigged things. Real original setup. Any suggestions on a methodical procedure to work my way through this. Think I got continuity at the clutch female connector side and also continuity at the clutch connector male side (not running/ign off)? Have multimeter in hand! Thanx Bill :party:
Racer
Joined: Dec 2001
Posts: 452
Likes: 2
From: Lynnfield MA
Re: A/C Troubleshooting (dpswmb)
Disconnect the clutch from the wiring harness, then try the test again.
If the fuse still blows, check for shorts to ground on the hot side
powering the clutch. If not, test the clutch using a circuit-breaker
protected power supply. That will at least narrow it down.
If the fuse still blows, check for shorts to ground on the hot side
powering the clutch. If not, test the clutch using a circuit-breaker
protected power supply. That will at least narrow it down.
Safety Car
Joined: Feb 2002
Posts: 4,942
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From: Gaffney, S.C.
Re: A/C Troubleshooting (SilvaDragon)
Look around for damage caused my Mice. They love to chew into wires and leave a fun mess to correct. I see this all the time. They nest on the intake manifolds and chew injector harnesses. :seeya
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Joined: Nov 1999
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From: belton texas
Re: A/C Troubleshooting (SilvaDragon)
Silvadragon, the fuse does not blow when disconnected. Lots of air comes out of the vents but of course it is really, really hot air here in Texas. We got through the wedding but I have to get it corrected soon. I have not looked at the harness side on the intake for several days but I am mixed up on the wiring circuit here. The connector that goes to the clutch is two-wire and one appears to have a resistence wire or loop wire or something on it. Is this circuit a power and ground to the clutch? And, is the two-wire setup on the clutch the same--power and ground? If this is the setup, I get continuity on the clutch side touching both leads from clutch when the connector is disconnected and I get continuity on the harness connector in the same ign off position. Like I said, the fuse does not blow when disconnected. Would this kind of indicate that the clutch is internally grounded???? thanks to all :_dupe: Oh, doing a circuit breaker test on the clutch is done how? Am I just jumping the connections to see that it trips the breaker or blows an inline fuse?
[Modified by dpswmb, 9:19 PM 7/21/2003]
[Modified by dpswmb, 9:19 PM 7/21/2003]
Racer
Joined: Dec 2001
Posts: 452
Likes: 2
From: Lynnfield MA
Re: A/C Troubleshooting (dpswmb)
Well, since the circuit doesn't trip with the clutch disconnected,
you have probably ruled out problems with the control module in
the dash, the wiring to the BCM, and the wiring to the clutch relay.
There are two things that need to be checked now, the clutch
itself, and the wiring from the clutch to the relay.
Since the clutch is a coil, it has very low resistance, so it may
seem to be internally shorted when connected to a low-impedance
volt meter, but in practice, that's a false reading. You really need
to jump 12 volts to the clutch to try and activate it, but if you
suspect that it is shorted, you don't want to simply wire it to the
battery, as the clutch draws fairly high current anyway.
But you're right, a test cable with a 30-amp inline fuse would
work very nicely as a test harness. If the fuse blows, the
clutch is toast. If you hear a nice sharp "click", then the
clutch is probably good, and the wiring needs testing.
I apologize, but I don't understand from your description
what you have tested, and why you conclude that the clutch
is internally shorted to ground.
you have probably ruled out problems with the control module in
the dash, the wiring to the BCM, and the wiring to the clutch relay.
There are two things that need to be checked now, the clutch
itself, and the wiring from the clutch to the relay.
Since the clutch is a coil, it has very low resistance, so it may
seem to be internally shorted when connected to a low-impedance
volt meter, but in practice, that's a false reading. You really need
to jump 12 volts to the clutch to try and activate it, but if you
suspect that it is shorted, you don't want to simply wire it to the
battery, as the clutch draws fairly high current anyway.
But you're right, a test cable with a 30-amp inline fuse would
work very nicely as a test harness. If the fuse blows, the
clutch is toast. If you hear a nice sharp "click", then the
clutch is probably good, and the wiring needs testing.
I apologize, but I don't understand from your description
what you have tested, and why you conclude that the clutch
is internally shorted to ground.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Re: A/C Troubleshooting (SilvaDragon)
Apply battery voltage to the clutch with a set of jumper cables. It it energizes the coil and pulls the clutch in the clutch should be fine If you get lots of sparks and no clutch action its shorted!
