01' F350 - AC Comp doesn't enable
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01' F350 - AC Comp doesn't enable
I have purchased a 2001 F350 4x4 V10 w/168000 miles. The heater controls and vent controls appear to be working correctly. With my manifold gauge, the AC system shows 100PSI on both sides. Regardless of the AC or AC MAX position, the AC compressor doesn't engage.
I have not yet pulled the wiring from the compressor to see if the clutch is getting voltage. However, I wanted to post here to determine if there are some obvious things I need to look for on this model that could cause this.
Also, does anyone know what the proper working (LO + HI) pressures are at 80F? What is the static (off) charge pressure normally for this model?
Thanks in advance for any guidance.
Nathan Smith
I have not yet pulled the wiring from the compressor to see if the clutch is getting voltage. However, I wanted to post here to determine if there are some obvious things I need to look for on this model that could cause this.
Also, does anyone know what the proper working (LO + HI) pressures are at 80F? What is the static (off) charge pressure normally for this model?
Thanks in advance for any guidance.
Nathan Smith
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Joined: Jan 2004
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From: St Louis
Welcome aboard. Always happy to see someone who has a manifold gauge set already hooked up.
I will assume you have already read the FAQs above.
Your static pressures are in the normal range. Usually, they run just a bit more than the ambient pressure measured in degrees F. When operating at 80F unloaded, you'd likely see low side pressures of between 25-40 psi and high side pressures between 175 and 250 with the compressor engaged.
First, check fuse F24 in the CJB. It supplies power to the series circuit of the MODE switch, the low pressure cycling switch, the high pressure containment switch, and the input to the PCM. The low pressure cycling switch is a very common failure. Disconnect the connector and install a jumper in the harness connector to see if the clutch will now engage. If so, replace the switch, a simple $20 repair.
Assuming the PCM is getting the A/C REQ signal above, it will, based selectively on its programming, energize the A/C Clutch Relay located in the BJB. The relay, when energized, will route power (supplied by BJB F6) to the A/C clutch coil with a return to ground on the low side of the coil.
I will assume you have already read the FAQs above.
Your static pressures are in the normal range. Usually, they run just a bit more than the ambient pressure measured in degrees F. When operating at 80F unloaded, you'd likely see low side pressures of between 25-40 psi and high side pressures between 175 and 250 with the compressor engaged.
First, check fuse F24 in the CJB. It supplies power to the series circuit of the MODE switch, the low pressure cycling switch, the high pressure containment switch, and the input to the PCM. The low pressure cycling switch is a very common failure. Disconnect the connector and install a jumper in the harness connector to see if the clutch will now engage. If so, replace the switch, a simple $20 repair.
Assuming the PCM is getting the A/C REQ signal above, it will, based selectively on its programming, energize the A/C Clutch Relay located in the BJB. The relay, when energized, will route power (supplied by BJB F6) to the A/C clutch coil with a return to ground on the low side of the coil.
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Thanks for the thorough reply. If I find some time tonight I'll start digging into this. I don't mind replacing fuses and sensors and a little 134. I hate replacing valves and clutches. Hopefully this will be simple.
Thanks again.
Nathan Smith
Thanks again.
Nathan Smith
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My problem is a worn clutch. I removed the one shim that was present and got it running. However it seems to engage with slip and the face of the clutch seems to have a noticeable wavy pattern from the edge to the center.
How many shims would have been present when new?
Is there a thickness spec. on the dis-engaged spacing? (I know, as small as you can get it without it engaging...)
I suspect the flex plate side of the clutch is a replaceable part? Any place on line that would be recommend to purchase?
Nathan Smith
How many shims would have been present when new?
Is there a thickness spec. on the dis-engaged spacing? (I know, as small as you can get it without it engaging...)
I suspect the flex plate side of the clutch is a replaceable part? Any place on line that would be recommend to purchase?
Nathan Smith
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Joined: Jul 2003
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From: Lawton, Oklahoma
I would go deeper in your evaluation. Usually you dont just get a wider air gap with age. You are probably seeing the bearings failing in the compressor and the air gap is caused by the shaft falling farther forward and opening too far. While it is possible to have a bad field on your clutch it is more possible with these vehicles to have a bad compressor. A closer evaluation by recovering the freon and inspection of the orifice tube would be in order IMHO
