Air Conditioner gremlins

I have tried to search for help with this but have had no luck with the search function.

I have a 2001 XJ that when I bought it had a slow leak in the AC system. Well this spring it turned into a large leak located in the evap core.

I finally broke down and tore out the entire dash to get to the hvac components, WHAT A PITA.

Well now that I have it all back together with a new evap, dryer, soft and hard lines, o-rings, evac and charge.

When I crank up the jeep in the morning everything works as it should. The gauges show proper psi, the compressor cycles on and off, and the temp out of the vents is in the lower 40's. I can rev the motor and let the coolant temp come up to 195-210. All good and woking.

BUT... as soon as I back out of the driveway and head down the road the compressor stops working. I turn around and head back to the driveway and nothing I do will make the compressor kick back in. The only thing that works is to turn it off and let it sit for an hr or so.

I did notice that when I turn the blend knob to floor the air does not come out at the floor, but when I turn it to defrost or vent it works as it should.

Maybe their is something going on with the vac pressure that makes the system think the air has been turned off? Is that even a logical train of thought?

Has any one else on here had this sort of issue?

Do you have any vacuum leaks?

I have not found any yet. I have a odb-2 scanner that shows BST/VAC around -5psi at idle and around -10psi at around 2000rpm.

Not sure if those are good or bad numbers.

well, I let it set for a couple hrs since the last test session.
Hooked up my gauges and cranked up the engine, turned on the AC all good. Held the RPM's as close to 1500-2000 as I could. watched the ac system cycle on and off for about 3 mins. When the gauges hit around, Low side 25 - High side 300, the fan would kick in and drop the psi back to around 35 - 200. It did this several times.

soon as I let it go back to idle the compressor clutch let off and would not come back on again.

I have tried to "jump" the low side switch connector to make the compressor clutch kick in but that does nothing. Is this the proper way to force the compressor to turn?

I can hear the rpm's rise when the AC switch is on, even when the compressor is off. I really wonder if there is something flakey with the clutch pulley.... maybe?..

Yes there is something flaky
What's happening the clutch is getting hot and making it weaker with already dirty and weak contacts.

Remove the compressor clutch and clean with a wire wheel.
Removing a washer or two (mine only had one) on the clutch shaft can also help, but you can go too far as well; mine currently has none.

Be sure to slowly and evenly work off the clutch disc

Can the washer be removed without removing the pulley? I have seen video of pulley removal that look extremely aggravating, and unless I am searching wrong none of the local autoparts places sell new ones.

Ahhh, I finally found a good youtube about the process
https://www.youtube.com/watch?v=V_s8AOqEMgw

Wow, RockAuto has the clutch pulley listed at $138. They sell the compressor with clutch for only $10 more.

Crazy

There is a low pressure switch and high pressure switch, and a thermostatic temp switch in the duct work. Try jumping the clutch directly to test the clutch. Sounds like a clogging AC system (did you pull a vacuum on it first and use a new dryer?), or faulty damper door, or a bad switch or T-stat switch in the duct work. The 25 psi/300 psi sounds very odd.

The E-fan should be on 100% of the time when the clutch is engaged!!!! That may be the real problem!!!!

gray_penguin said:

well, I let it set for a couple hrs since the last test session.
Hooked up my gauges and cranked up the engine, turned on the AC all good. Held the RPM's as close to 1500-2000 as I could. watched the ac system cycle on and off for about 3 mins. When the gauges hit around, Low side 25 - High side 300, the fan would kick in and drop the psi back to around 35 - 200. It did this several times.

soon as I let it go back to idle the compressor clutch let off and would not come back on again.

I have tried to "jump" the low side switch connector to make the compressor clutch kick in but that does nothing. Is this the proper way to force the compressor to turn?

I can hear the rpm's rise when the AC switch is on, even when the compressor is off. I really wonder if there is something flakey with the clutch pulley.... maybe?..

Click to expand...

Well taking the shim out of the clutch did the trick. Still have to figure out why the e-fan is waiting so long to come on and why it cycles instead of stays on.

Its 95+ outside now with the compressor running my gauges are reading 45 - 325 when the e-fan comes on and then it goes down to 45-225 when the fan cuts off.

The coldest the air got in the vents on my test drive was 64. which seems high to me. (could be the damper door I guess)

On a side note, this is a CA emissions XJ and I do have issues with heat soak in the summer. I read something about making the e-fan come on and stay on manually with a switch in the dash. Which supposedly can help with pushing the heat out of the engine compartment. Maybe I should look into that and kill two birds with one stone...

Check a wiring diagram. The PCM is wired to turn on the E-fan when it turns on the AC clutch. Look for the power path and find out what went bad. Right now the PCM is using the coolant temp highs to turn on the E-fan and that leaves the pressure switches to cut of the compressor clutch before it blows the condenser or a hose up.

That shim controls the air gap on the clutch. I need to do that to mine someday. I have two duct tape-chewing gum tricks I use LOL.

My '00 does not run the efan with the AC on. It only kicks on when the temp gets high. It's been this way since I bought it 5 years ago. No issues - should I be checking into this? I thought the late models did NOT run the fan with the AC all the time.

CarbonXJ said:

My '00 does not run the efan with the AC on. It only kicks on when the temp gets high. It's been this way since I bought it 5 years ago. No issues - should I be checking into this? I thought the late models did NOT run the fan with the AC all the time.

Click to expand...

My 96 ford and 2001 Saturn both run the e-fan all the time while the clutch is engaged. Detroit does some poor things sometimes so I do not know if they lost their sanity in your year jeeps, and my jeeps are 87-89. I would would want mine to run all the time the clutch is engaged to insure lower head pressures, less wear on the compressor and belts and less chance of exploding a hose or condenser...Just look at the huge head pressure differences he posted!! It it would also reduce the load on the engine and improve MPGs.

Then yours is using the high pressure switch to cycle the e-fan.

"Its 95+ outside now with the compressor running my gauges are reading 45 - 325 when the e-fan comes on and then it goes down to 45-225 when the fan cuts off."

I think my ford turns the e-fan on low when the clutch engages or on high if it was already on. It is 2 speed. Not sure if the Saturn is 2 speed. I run my e-fans all the time with a by pass in the summer, 87-89 Jeeps.

gray_penguin said:

Well taking the shim out of the clutch did the trick. Still have to figure out why the e-fan is waiting so long to come on and why it cycles instead of stays on.

Its 95+ outside now with the compressor running my gauges are reading 45 - 325 when the e-fan comes on and then it goes down to 45-225 when the fan cuts off.

The coldest the air got in the vents on my test drive was 64. which seems high to me. (could be the damper door I guess)

On a side note, this is a CA emissions XJ and I do have issues with heat soak in the summer. I read something about making the e-fan come on and stay on manually with a switch in the dash. Which supposedly can help with pushing the heat out of the engine compartment. Maybe I should look into that and kill two birds with one stone...

Click to expand...

Again, yours may just need a cleaning. Good to know progress tho
I second Carbon; mine doesnt run all the time either, as designed. I had previously asked the same. Someone posted the operation and it was only on with two parameters; niether were just on with comp. From what i can remember, one condition is temp and the other is pressure.

My 97 cycled the e-fan with the a/c on and I knew that probably wasn't right. The PO had just installed a new e-fan, I took apart the connection at the fan, cleaned it up and now it stays on all the time with the a/c on, that was my problem, might want to check that out.

digginit said:

My 97 cycled the e-fan with the a/c on and I knew that probably wasn't right. The PO had just installed a new e-fan, I took apart the connection at the fan, cleaned it up and now it stays on all the time with the a/c on, that was my problem, might want to check that out.

Click to expand...

Thanks, I found it hard to believe that was a factory change on the AC-e-fan operation. I wonder if some aftermarket e-fans are not wired right also?

CarbonXJ said:

My '00 does not run the efan with the AC on. It only kicks on when the temp gets high. It's been this way since I bought it 5 years ago. No issues - should I be checking into this? I thought the late models did NOT run the fan with the AC all the time.

Click to expand...

If that is the OEM setting for 00, a factory change from prior years, maybe it is why those rigs have heat issues?

The heat issues usually arise from the CAFE emission on all 01 and some 00