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absolutely, dont forget to check in the fuse box, look at the ac clutch relay and diode to see if the terminals there are corroded
Yep-yep...those are on my list to check as well before doing anything else, hence why I have a thread on getting my hands on an owner's manual which (thanks to this forum) I now have, so I can identify which components in fuse box are related to the A/C system. I'll test the diode as well as look at those contacts. And I never visually check fuses but always check resistance.
i notice in your other post your alt is most likely bad, if your system voltage is low due to a bad alternator, the 9v you are reading at the compressor might be caused by a discharged battery? i would get the alt fixed first then check the operation of the clutch
Good points. The battery is brand new as of a couple months ago...got a 750CCA battery because of the supercharger. The alternator seems to be charging the battery. It always starts and without laboring, and it's a daily around-town driver. I think the alternator is doing its job, just may be singing its swan song. Battery voltage is good and 13.5+ volts at the batter when the engine is running. I suspect a bad connection or a voltage leak due to a damaged wire or something of the like being the cause of the low voltage at the A/C compressor, but obviously I've got some things to do first before chasing that down...test the compressor clutch with external powe source, check the A/C related bits in the fuse box, and I'm going to get the alternator tested even though, based on comments here and past experience, I'm 99% sure I'll be putting a new one on. But that's such an easy job...so yeah I'll take care of that first and leave chasing down the low voltage issue at the A/C compressor til after those other things in case something along the way clears that up.
So I check again (power at the compressor) and it remains 9V +/-. I found the A/C clutch fuse which I tested with my DMM...fuse seems good. And the input to the fuse is about 13.5V with the car running. Same thing with the A/C "pressure" fuse...fuse is good and the input to the fuse is 13.5+ volts with engine running. I hooked the DMM back up the A/C compressor plug and at first it was still 9V, then it popped up to 13+ volts. Hooked it back up again and...nothing. I was going to hook up my bench supply to power the clutch just to rule out whether or not the clutch is shot, but like a dummy I quickly realized my bench supply lacks oomph. 5-50VDC regulated, but only up to 500mA. Not enough to kick that electromagnetic clutch into action. I'll have to rig a way to direct connect it to the battery. Too late tonight.
The low pressure side has WAY too much pressure. I think the previous owner took the hammer approach and thought he'd get it work by pumping the system way full of refrigerant. Dumba$$. At least nothing has blown and the system actually seems to be holding this pressure, but I'm working on dropping it before I kick the compressor on and test. So I'm dealing with that, while rigging up a way to jump the clutch direct from the battery.
Another question: I found those two fuses above (high pressure fuse and clutch fuse) but no relays related to the A/C or diode. Can somebody tell me where those are located?
first what is your low side pressure? if its lets say 80 deg out the low side pressure should be close to 80psi static (compressor not operating) r134 in a non operating system will almost mirror ambient air temp, if the underhood temps are higher, the psi will be as well.
the ac relay is intenral of the ccrm (constant control relay module)
next steps, ccrm is located on the rh fender, check pin 21 for fvoltage, this feeds the ccrm, if you have 12v there then check pin 23 with ac on and see if you have the same voltage reading there, if its low there but good on pin 21 then the ccrm is the cause of your voltage drop. good luck
Maybe the low-side pressure wasn't so high then. I'll have to confirm when I get home what it was, but I'm thinking it wasn't above 80psi, and it was about 80 degrees out.
Am I correct in assuming I will need to find a way to probe pins 21 and 23 with the CCRM connected (i.e. stuff in a couple small gauge wire flying leads for instance)?
oxfordgt I do appreciate the link to the Ford FSM. I am reading it. Its almost 4400 pages so it ma take a bit. And its for an '03 vs '01 so I'm being careful that not all may apply.
Maybe the low-side pressure wasn't so high then. I'll have to confirm when I get home what it was, but I'm thinking it wasn't above 80psi, and it was about 80 degrees out.
Am I correct in assuming I will need to find a way to probe pins 21 and 23 with the CCRM connected (i.e. stuff in a couple small gauge wire flying leads for instance)?
yes you should back probe the conector with it connected, i dont have the connector in front of me, but i often use a paper clip, or very small piece of wire to back probe the connector, but remember to e gentle, you dont want to damage the pin or the hardshell of the connector.
oxfordgt I do appreciate the link to the Ford FSM. I am reading it. Its almost 4400 pages so it ma take a bit. And its for an '03 vs '01 so I'm being careful that not all may apply.
All the same car when it come to the electrical part. No need to read the whole thing skip to page 3064 pinpoint test c: The a/c does not operate. That pinpoint test is the correct test to find the problem with your A/C
07-20-2015, 03:54 PM
