1990 Civic LX 1500 A/C blows warm / intermittent clutch / loss of 12V
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Joined: Jul 2008
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From: San Angelo, TX, United States
1990 Civic LX 1500 A/C blows warm / intermittent clutch / loss of 12V
I've been in my garage for a week working on this problem and I'm getting nowhere.
Searched the internet and found this site...looks like there's a lot of knowledge here so I thought I'd run it pass you guys.
I see this as two problems;
1. The 12v supply to the clutch drops out after the vehicle warms up 5 minutes or longer and the A/C is turned off and back on OR the vehicle is turned off and back on, the clutch does not re-engage. Fan stays on. When this happens the vehicle surges from 1200RPMs TO 2000RPMs, continuously cycling till I either turn the A/C off or the vehicle off.
2. When the clutch is engaged the vent blows warm.
Here's the readings;
H 190
L 40
Garage temp 85F
Vent temp 70F
System has been vacuumed and recharged (on 7/22 ). I don't have a recovery system, charge with individual 12oz cans, approx 21oz of freon. New pressure switch installed prior to recharge/vacuum.
Voltage reading at input to thermal switch (from wiring harness) is 13.5V with clutch and fan engaged.
When clutch doesn't re-engages after turning A/C off and back on OR turning the car off and back on, reading at the wiring harness (input to thermal switch) is ZERO volts but the fan is on.
Jumper from battery to thermal switch or directly to clutch coil, the clutch stays engaged as well as the fan.
Bypassed the pressure switch with a jumper to the 2-wire connector. Same problems as indicated above; Clutch comes on but after the vehicle warms up 5 minutes or longer and the A/C is turned off and back on OR the vehicle is turned off and back on, the clutch does not re-engage. Fan stays on.
Ohm'd out 2-wire connector to the pressure switch with A/C button pushed in, blower switch to max;
one side to ground - 2.7M ohms
other side to ground - 1.7 ohms
Temp Sensor Module module bypassed by jumper; readings/car operation the same whether bypassed or connected.
Okay.............all that said, is it possible this problem is a product of ECU? I ask this because of loss voltage to the clutch coil and because of the 1200-2000RPM surges?
The 12v loss has been traced to the best of my ability and I still can't find a failed or intermittent part.
I've had many a A/C failure on other vehicles in the past but nothing that induce a 1200-2000RPM cycling surge.
Any of you guys got any thoughts on this..??
Searched the internet and found this site...looks like there's a lot of knowledge here so I thought I'd run it pass you guys.
I see this as two problems;
1. The 12v supply to the clutch drops out after the vehicle warms up 5 minutes or longer and the A/C is turned off and back on OR the vehicle is turned off and back on, the clutch does not re-engage. Fan stays on. When this happens the vehicle surges from 1200RPMs TO 2000RPMs, continuously cycling till I either turn the A/C off or the vehicle off.
2. When the clutch is engaged the vent blows warm.
Here's the readings;
H 190
L 40
Garage temp 85F
Vent temp 70F
System has been vacuumed and recharged (on 7/22 ). I don't have a recovery system, charge with individual 12oz cans, approx 21oz of freon. New pressure switch installed prior to recharge/vacuum.
Voltage reading at input to thermal switch (from wiring harness) is 13.5V with clutch and fan engaged.
When clutch doesn't re-engages after turning A/C off and back on OR turning the car off and back on, reading at the wiring harness (input to thermal switch) is ZERO volts but the fan is on.
Jumper from battery to thermal switch or directly to clutch coil, the clutch stays engaged as well as the fan.
Bypassed the pressure switch with a jumper to the 2-wire connector. Same problems as indicated above; Clutch comes on but after the vehicle warms up 5 minutes or longer and the A/C is turned off and back on OR the vehicle is turned off and back on, the clutch does not re-engage. Fan stays on.
Ohm'd out 2-wire connector to the pressure switch with A/C button pushed in, blower switch to max;
one side to ground - 2.7M ohms
other side to ground - 1.7 ohms
Temp Sensor Module module bypassed by jumper; readings/car operation the same whether bypassed or connected.
Okay.............all that said, is it possible this problem is a product of ECU? I ask this because of loss voltage to the clutch coil and because of the 1200-2000RPM surges?
The 12v loss has been traced to the best of my ability and I still can't find a failed or intermittent part.
I've had many a A/C failure on other vehicles in the past but nothing that induce a 1200-2000RPM cycling surge.
Any of you guys got any thoughts on this..??
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Frenchie745
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Oct 14, 2013 01:07 PM
