Got stuck trying to figure out A/C problem

SBarber1

SBarber1

TJ Enthusiast
Joined
Jan 19, 2017
Messages
104
Location
Navarre, FL, United States
AC wasnt getting cold, at all.

All other functions of system worked.

Noticed fan clutch wasnt engaging.

Bought a can of refrigerant and added a little to see if it would engage. It did engage but only for very short bursts not really cooling anything. Added a quite a bit more and it did start to engage more often just at small bursts.

Drove and bought some gauges not wanting to make things worse. Now it got cold but only while driving.

Got home hooked up gauges. (Outside temp 88) Low pressure inlet was high and high pressure was bouncing high to low as clutch would engage. Would not get cold at idle. 80low 100/200high. (My idle is low around 500 or a little less)

I tested it by adding a little weight to gas pedal and got rpm to about 1000. Clutch engaged and stayed that way. Readings normalized after a little bit. High side at 200 low side at 40 and cabin got frosty cold. As soon as i removed weight and let rpms drop issues started again.

So is this an issue caused by the low rpms or clutch going out?

Obviously it seems like there is a leek as I put in a good amount of refrigerant . The high side schrader valve was leaking pretty good when i removed gauges and it took some work to get it to stop. I will replace those. Maybe that was it. I plan on getting the system evacuated and filled professionally if I can get the rest figured out.

I live in FL so my AC is pretty important to me right now 😆

Any thoughts?
 
Yes.... it does sound like you have a leak in the system; whether it is a leaking service port or another location will only be known when you take the Jeep in for A/C servicing. Part of the problem with the pressures you were seeing is that you needed more air flowing (you Jeep wasn't moving) thru the condenser to remove heat from the refrigerant moving thru the condenser. The more heat that is removed from the refrigerant the lower the pressures and the cooler the air coming from the vents.
 
CharlesHS said:
Yes.... it does sound like you have a leak in the system; whether it is a leaking service port or another location will only be known when you take the Jeep in for A/C servicing. Part of the problem with the pressures you were seeing is that you needed more air flowing (you Jeep wasn't moving) thru the condenser to remove heat from the refrigerant moving thru the condenser. The more heat that is removed from the refrigerant the lower the pressures and the cooler the air coming from the vents.
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Clutch is not staying engaged at idle and is not cold. Any idea why clutch wont stay engaged at low rpm? Works when I increase rpm while parked.
 
Two comments. Your idle speed is too slow, figure that out first. Then install a set of gauges after the idle problem is fixed and tell us what the gauges are reading at idle and if there is any unusual needle movements.
 
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SBarber1 said:
Clutch is not staying engaged at idle and is not cold. Any idea why clutch wont stay engaged at low rpm? Works when I increase rpm while parked.
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There could be a problem with the low pressure switch or the compressor clutch. You may be low on refrigerant, but until you connect a gauge manifold to check operating pressures while idling and at higher engine speeds; you wont know what your A/C system is doing or why.
 
CharlesHS said:
There could be a problem with the low pressure switch or the compressor clutch. You may be low on refrigerant, but until you connect a gauge manifold to check operating pressures while idling and at higher engine speeds; you wont know what your A/C system is doing or why.
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I did attach gauges pressures are in post.
 
Ok so a new Mopar IAC and idle is running smooth and around 750.

Clutch is ingaging and ac is blowing cold at idle. Big puddle of water on ground in no time. Woohoo

So I go to hook up gauges to see what they read then I get really confused, not that hard.

This doesn't make sense to me, so before I screw anything up? The stickers on the high and low side of the connectors and gauge knobs show them opening and closing in the opposite direction? However all knobs rise when turned counter clockwise and lower when turned clockwise.... Is it just me?

20200908_203718.jpg
 
With the R134a manifold.... once the hose connections are snapped onto the factory service ports; you need to screw in the knobs on those connections to access the system pressures. The knobs actually on the manifold will only be turned when you are going to evacuate or charge the system.
 
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Generally, the leaks tend to be found at the schrader valves, the o-rings at the quick connects, and the accumulator (it has a tendency to rust due to the steel construction and the condensation). You can easily, inexpensively, and quickly replace all of these components yourself. I recently replaced my rusted accumulator with one i bought from jeepair.com. It came with the o-rings, and I also bought extra o-rings and replaced all of the other quick connect o-rings. Add about one ounce of PAG oil.

The best way to recharge this system is to evacuate and wait 24 hours. You should be able to reach a vacuum of one atmosphere and hold that vacuum for a full 24 hours. Weigh in the 134a with a small scale. It's the only way to be sure you have the correct amount of refrigerant. 134a is available without an EPA license-I bought a tank off Amazon some years ago. You can buy or borrow a vacuum pump if you don't have one.

One thing-the bend on the lower line of the jeepair-sourced accumulator is higher/taller and sharper than the factory accumulator. It has a tendency to interfere with the refrigerant line that comes out of the firewall directly over the accumulator. You may need to use a tubing bender and adjust the line that comes out of the firewall to gain the clearance needed. Do not try to bend any of these by hand-it will be a poor and expensive ending.
 
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When measuring vacuum; it is best to measure in microns with a digital meter. The analog gauge on a refrigerant manifold cannot measure minute changes in vacuum (indicating a leak or refrigerant boil off) the same way a digital meter can. My eyes cannot detect minute changes in needle defections, but with the digital its a no brainer.

One atmosphere is approximately 29.92 inHg or 110 microns.
A micron reading of 250 microns should be held for 6-12 hours to provide a proper indication although most technicians allow for 1-2 hours to be sufficient. This is usually the rule for stationary applications.
 
@CharlesHS, it's a great point, and I strongly concur. I don't have digital capability, so I like to use the 24 hour method. I can definitely tell if there's movement over a 24 hour period.
 
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CharlesHS said:
There could be a problem with the low pressure switch or the compressor clutch. You may be low on refrigerant, but until you connect a gauge manifold to check operating pressures while idling and at higher engine speeds; you wont know what your A/C system is doing or why.
Click to expand...
The clutch on mine had the center broken out of it in a perfect ring where the rubber(?) is between the inner and outer parts. 95% of the time when my clutch would try to engage, it would just pull the outer ring and spin it around the inner portion and the actually compressor itself would never spin. Got a new clutch and just changed that part of it out and it worked great after that.
 
Years ago I too used the tape on the gauge set to identify needle movement indicating a leak or refrigerant boiling off. While the felt tipped pen or tape placed on the gauge face do indicate if the needle moves; it does not indicate the rate of movement where a digital micron meter can indicate within a few minutes. Using a analog gauge can take several hours or more to determine the needle is actually moving.
The digital micron meter makes determining if there is a leak; much quicker and more easily determined.
Using the gauges vs micron meter comes down to a matter of preference and an the investment in tools.
 
CharlesHS said:
Years ago I too used the tape on the gauge set to identify needle movement indicating a leak or refrigerant boiling off. While the felt tipped pen or tape placed on the gauge face do indicate if the needle moves; it does not indicate the rate of movement where a digital micron meter can indicate within a few minutes. Using a analog gauge can take several hours or more to determine the needle is actually moving.
The digital micron meter makes determining if there is a leak; much quicker and more easily determined.
Using the gauges vs micron meter comes down to a matter of preference and an the investment in tools.
Click to expand...
Sometimes the investment for a DIY doesn't make sense as is the case in this situation. If you run a shop, where the majority of your business is AC work, sure quicker is better. Here drink a few beers and come back to it.
 
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