High A/C Pressures

[Benp]

I'm trying to help a co-worker get his A/C working on his '96 Ranger and need a little assistance. I hooked up my gauges to his truck and initially got 110 psi on the low side and 80 psi on the high side? The ambient temp was 85 degrees. The clutch on the compressor does not engage. I depressed the low side schrader valve and lowered the pressure down to 10psi but as soon as I turn the truck on it jumps back up to 80psi. Nothing but warm air being released from the low side valve. I lowered the pressure back down to almost 0psi and emptied about half a can of R134 w/dye in while the engine was off since I was worried about the rapid pressure build up with the motor running. I tried jumping the low pressure switch but no clutch action. With the engine running the low side is 80psi and high is 100psi?

What would cause the high low pressure reading? How do I confirm 12v are getting to the clutch?

Thanks in advance for any help you all can lend!

BenP
Atlanta, Ga

 

[ghosttrain2]

you are reading static pressure with out the clutch engagement. Normal system readings should be read with the a/c clutch engaged. Check fuses first, if you have power to the clutch,and have an ohm meter,check to see if the clutch coil is open.

 

[Benp]

Thanks! I don't have my ohm meter with me but I'll check the fuses.

 

[Benp]

So...... I tell my coworker I need to check the fuses in his truck and he says "the one that kept blowing out so I stopped replacing it?"

Fuse #18 is a 15 amp fuse that is blown and I'm guessing where I need to start. Anyone have a wiring diagram for a '98 Ranger XLT 3.0 for the a/c system they can publish or share?

He also advised me that his lighter socket has been dead too but the fuse diagram from Autozone shows that to be a different circuit (fuse #17, 30a).

Are there any known common areas that result in shorts for the A/C circuit? Chaffed wires?

Thanks!

Benp

 

[ranger7ltr]

You might want to check the #1 mini fuse and the #2 relay in the battery junction box under the hood.. That fuse controls the a/c relay which controls the clutch...

#17 fuse indeed controls the cigar lighter and the OBD-II connector... #18 controls the unlock relays and the drivers lock relay...

I wouldn't be concerned about the pressure differences until you get the compressor running...Static pressures really means nothing to the operational condition of the a/c system except that the system is holding pressure...

Did the system just stop working or did the compressor lockup or what happened to stop the system from working? We know the system holds refrigerant and should have had enough to trigger the low pressure switch...

So...... I tell my coworker I need to check the fuses in his truck and he says "the one that kept blowing out so I stopped replacing it?"

Fuse #18 is a 15 amp fuse that is blown and I'm guessing where I need to start. Anyone have a wiring diagram for a '98 Ranger XLT 3.0 for the a/c system they can publish or share?

He also advised me that his lighter socket has been dead too but the fuse diagram from Autozone shows that to be a different circuit (fuse #17, 30a).

Are there any known common areas that result in shorts for the A/C circuit? Chaffed wires?

Thanks!

Benp

 

[Benp]

I'll check those fuses and relays out on Monday when I see the truck again. Can you confirm that the #1 mini fuse controls the A/C? The only reason I ask is the fuse box diagram on the Autozone website shows #18 to be the A/C fuse. My coworker is suppose to bring his owners manual in on Monday in the event I can't get confirmation.

According to the owner of the truck the A/C just stopped working one day. No noise no smoke nothing out of the ordinary. He's not very mechanical which is why I stepped in to help. He told me about his last trip to the local Brakes R Us chain where they charged him over $500 to replace pads and rotors on the front of his truck. I couldn't bear to see him get ripped off again if it was something minor to get his A/C working again.

Thanks!

Benp

 

[ranger7ltr]

The mini fuses are in the fuse box under the hood...

According to the Ford service manual for the 98 Ranger I have there are 2 fuse panels. One in the truck and one under the hood.. The A/C relay is powered by the mini fuse in the underhood panel...

The only reference I see to anything a/c related in the inside truck fuse panel is the #10 fuse which, I believe, would control the blower motor... It also controls the GEM module, Blend door actuator, speed control module, emergency flashers, and the shift lock actuator...

There is a link one of the members here has to get to most of the Ford service manual disks... I will see if I can find it so you can d/l it and view the same information I have already...

Good luck with this one.. Sounds like there may be more wrong than the a/c ....

 

[stang1970]

hey check the wire harness that comes from the computer then across firewall and then goes behind the engine.

Mine kept blowing the fuse, turns out the harnes was rubbing on the back of the engine and shorted out the wires