AC Clutch/Fan won't engage
#1
AC Clutch/Fan won't engage
Been trying to get the ac system on my wife's 01 Civic LX working for the past day or so. Here's what I've got going on;
Symptoms : HVAC motor blows ambient temp air when ac system is engaged. Neither the fan or the compressor clutch engage when the ac is turned on.
What I've Done:
-Fuses (engine compartment & cabin)
-Relays (engine compartment)
-Replaced AC Condenser
-Replaced AC Compressor
-Evacuated System
Anybody got any thoughts on what my next step should be?
Symptoms : HVAC motor blows ambient temp air when ac system is engaged. Neither the fan or the compressor clutch engage when the ac is turned on.
What I've Done:
-Fuses (engine compartment & cabin)
-Relays (engine compartment)
-Replaced AC Condenser
-Replaced AC Compressor
-Evacuated System
Anybody got any thoughts on what my next step should be?
#2
The usual reason for this is a bad MCU (part of the dash fuse box). Typically there are other symptoms like the dome light and keyless entry won't work either.
Did you recharge after evacuating? System will not run with no pressure. If there is pressure, check that the pressure switch is closed.
Then do a control panel self test. Check if the evaporator temperature sensor is plugged in. (The control panel self test should detect that.)
Did you recharge after evacuating? System will not run with no pressure. If there is pressure, check that the pressure switch is closed.
Then do a control panel self test. Check if the evaporator temperature sensor is plugged in. (The control panel self test should detect that.)
#3
Climate Control
General Troubleshooting Information 21-104
How to Retrieve a DTC
The Climate Control Unit has a self-diagnosis function.
Running the Self-diagnosis Function
Turn the fan switch OFF.
Press the recirculation control switch and the rear window defogger switch.
While holding the both switches down, turn the ignition switch ON (II), then release the both switches. The recirculation indicator light and the rear window defogger indicator light come on. The recirculation indicator light goes off 2 seconds later and the A/C indicator light comes on (if so equipped), then the self-diagnosis will begin. About 10 seconds later, the self-diagnosis will finish and the A/C indicator light goes off. The recirculation indicator light will blink the Diagnostic Trouble Code (DTC) to indicate a faulty component. If no DTC's are found, the indicator light will not blink.
NOTE: LHD type is shown, RHD type is symmetrical.
FAN SWITCH
RECIRCULATION INDICATOR LIGHT
A/C INDICATOR LIGHT
REAR WINDOW DEFOGGER INDICATOR LIGHT
REAR WINDOW DEFOGGER SWITCH
RECIRCULATION CONTROL SWITCH
Example of DTC indication Pattern (DTC 3)
Resetting the Self-diagnosis Function
Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work, run the self-diagnosis function again to make sure that there are no other malfunctions.
General Troubleshooting Information 21-104
How to Retrieve a DTC
The Climate Control Unit has a self-diagnosis function.
Running the Self-diagnosis Function
Turn the fan switch OFF.
Press the recirculation control switch and the rear window defogger switch.
While holding the both switches down, turn the ignition switch ON (II), then release the both switches. The recirculation indicator light and the rear window defogger indicator light come on. The recirculation indicator light goes off 2 seconds later and the A/C indicator light comes on (if so equipped), then the self-diagnosis will begin. About 10 seconds later, the self-diagnosis will finish and the A/C indicator light goes off. The recirculation indicator light will blink the Diagnostic Trouble Code (DTC) to indicate a faulty component. If no DTC's are found, the indicator light will not blink.
NOTE: LHD type is shown, RHD type is symmetrical.
FAN SWITCH
RECIRCULATION INDICATOR LIGHT
A/C INDICATOR LIGHT
REAR WINDOW DEFOGGER INDICATOR LIGHT
REAR WINDOW DEFOGGER SWITCH
RECIRCULATION CONTROL SWITCH
Example of DTC indication Pattern (DTC 3)
Resetting the Self-diagnosis Function
Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work, run the self-diagnosis function again to make sure that there are no other malfunctions.
#4
OK, went out and was messing with the car this morning, got everything put back together, took my gauges off and did a low side charge (from vacuum). The system took almost 2 12oz cans (total of right around 17.5-18oz) of 134A, which is right in between the min and max levels according to the service sticker. However, it looks like the compressor clutch is not engaging. The fan kicks on now (figured out it was the low pressure switch that was keeping the condenser fan from kicking on before), but not blowing cold air. Is there any way to test the compressor clutch to see if it's bad? I'm assuming it's the clutch I'm looking at anyway (complete HVAC newb), it's the metal plate on the outside of the pully right? My understanding is that this plate has an electro-magnet on it, and when the ac is not turned on it free floats, but when the ac is kicked on, current energizes that magnet and it spins the compressor.......am I right on this or should I keep reading?
If the clutch does turn out to be bad, is there any way to replace just the clutch without evacuating the entire system (again) and removing the compressor (again). I guess that's what I get for buying used parts, but I really didn't want to spend the $500 the dealership was asking for a new compressor.
If the clutch does turn out to be bad, is there any way to replace just the clutch without evacuating the entire system (again) and removing the compressor (again). I guess that's what I get for buying used parts, but I really didn't want to spend the $500 the dealership was asking for a new compressor.
#5
Do both fans start, or just one? If only the fan on the right side works, the fan / compressor fuse is probably blown. If both fans start the compressor relay could be bad, swap it with one of the other same type relays on the car.
Check if power is going to the compressor wire. You can also disconnect the wire and jumper it to the battery, the clutch should pull in. (DO THAT ONLY WITH THE ENGINE OFF. Jumping the compressor with the engine on is likely to create an over-pressure.) With the engine off and clutch energized you can also press on the clutch plate and see if it snaps down.
The clutch can be worked on with the system charged. You may need to unbolt the compressor but don't disconnect the lines.
Check if power is going to the compressor wire. You can also disconnect the wire and jumper it to the battery, the clutch should pull in. (DO THAT ONLY WITH THE ENGINE OFF. Jumping the compressor with the engine on is likely to create an over-pressure.) With the engine off and clutch energized you can also press on the clutch plate and see if it snaps down.
The clutch can be worked on with the system charged. You may need to unbolt the compressor but don't disconnect the lines.
#6
Both fans are running when the ac is switched on. All fuses and relays are functioning properly. I took a DMM to the wire running to the compressor, and it's getting +12v when the AC is switched on, nothing when the AC is off. Clutch is not engaging when the power is applied, so I'm pretty certain that that's the issue. So now comes the issue of replacing the clutch......everywhere I've checked only sells the the clutch with the compressor. I've seen a few repair kits on ebay, but I'm nervous about purchasing anything off of ebay, I'd much rather go through NAPA, Auto Zone, Advanced, ect. I've been told that it's generally the bearing that goes out in the clutch, if I can find just the bearing, would that be a viable option? Thanks for the help so far, it's much appreciated. Hoping to get this done asap, we've got a few 100+ degree days coming up that my wife is not really looking forward to it :S
#7
One more test, unplug the compressor wire and measure resistance through the compressor to ground. It should be 3 or 4 ohms. If you find open circuit either the thermal protector or the clutch coil is open, check them individually. If resistance is OK you should be able to make the clutch work by just taking out shim washers to reduce the gap.
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