Yup, another '98 TJ with no A\C

Actually the tube FROM the firewall/evaporator TO the low side of the compressor should be cold. The one From the Compressor high side to the condenser should be hot. From the condenser to the firewall/Evaporator should be warm/less hot then the one from the compressor out to the condenser.

I would first suspect the air flaps since the compressor is working. If you were low on freon from a leak, the compressor not be working.

JoBo

Diezmon did pass the time by typing:

Your just slightly low on refrigerant. The outlet tube should be colder than the inlet tube (expansion of the gas) (outlet about 5-6 C or 8-10F colder than inlet) Outlet is the big hose to the accumulator, inlet is the hardline from the condenser

Both tubes going through the firewall should be cold.

The line from the compressor to the condensor is indeed hot. But, my line from the condensor TO the firewall/evap is very cold.

Where exactly is the pressure change supposed to be in the system? Based on what I'm seeing, it seems like the pressure change is IN the condensor (in is hot, out is cold) does that sound right?

So, next question.. what's a good way to verify the air flaps? All cables are working, or seem to be working. I wish I could see into the housing w/out taking the d*mn thing out!

Tim

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According to my refill kit gauge, the pressure is ok. It's a kit that attaches to the low pressure side. I'm afraid of adding more from the can, since that would put me in the "RED" zone..

I suppose I should get a more accurate gauge, huh? ;)

Tim

Diezmon did pass the time by typing:

Refill kit gauges are not very accurate and 134a systems are extremely picky about how much gas is in the system. Actually the old pressure system is not what's recommended. It's either drain/evac/refill with known weight or go by the temperature delta at the evaporator inlet and outlet.

Yep.

If you really want to do more than stand there with your thumbs in your pockets, saying "No ma'am, it sure isn't cooling enough", then you need a high and low side gauge set, and a basic air conditioning manual. A thermometer to measure the output air temperature to the cabin is a big help too.

If you are getting any cooling at all, then chances are really, really good that you have a simple leak, and low refrigerant. You can do what all the other shade tree mechanics do, add a 13 oz. can of refrigerant, and hope for the best. Usually when I get a vehicle, with the symptoms you are describing, this fixes it for a while. Sooner or later, you will have to find that leak though. They get worse with time, you know. Soap and water mixture in an old Windex spray bottle is better than nothing. Red or UV leak detector in a can can be good, too.

A book like the basic repair manual from acsource.com is probably the best investment you can make at this point.

Earle

FWIW (and I take no responsibility for you blowing out your AC system) My old Mustang GT had extremely weak air and the same sort of kit showed the pressure to be good just like yours... Charging it anyway resulted in nice cold air and no explosions. I did bleed, um I mean... some of the old pressure _accidentally_ escaped before I stubbornly re-charged the system.

PROBABLY not what I should have done so take it for what it's worth.

Many people think that a gauge set is a single low side gauge, connected to a low side coupler and a can tap. If you have Lady Luck on your side, once your system stops cooling, the low side pressure will be about ten, but there will be enough refrigerant to actuate the switch that keeps the compressor engaged. After a 13 oz. can of refrigerant it will start working again, with a low side pressure of 25-30. This is hardly scientific, in that you have little chance of getting the precise amount of refrigerant that R134a systems like to have. It is even less scientific, than attempting to charge an R134a system using high and low side gauges.

As another poster points out, if the system "accidentally" discharges itself, you will now have the opportunity to install the correct amount of refrigerant.

Earle

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If memory serves me, the Orifice Tube on this CCOT system is located in the hose that exits the Condenser (locating in this position reduces refrigerant flow noise in the cabin). Your description indicates low charge. It might be a leak or it might just be normal system leakages over the 8 years of service this vehicle has seen. After recovering the remaining refrigerant I would replace the o-rings at all of the evaporator connections and replace the Accumulator (the dessicant is probably saturated after 8 years of life). Recharge the system and add 50% of the compressor oil (some will be lost with the Accumulator change) and you should be good to go. (assuming that you've made a good visual inspection of the other parts of the system to eliminate obvious problems). reboot

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Not possible to diagnose this problem conclusively without pressure readings. What is the outside air temperature?

98 TJ, I assume using r134a if the ambient air temp is around 90+ then your high side readings will be in the 275 - 310 psi range R134 runs at higher pressure than r12. Your low side readings should be in the 25-35 psi range. Stick a thermometer in the center register and get a reading - engine running around 1200 rpm, air on recirc, fan on high.

If the ac is low, then the compressor should be cycling on-off due to the low pressure cutout switch opens the clutch circuit around 20 - 25 psi. The goal is to keep the evaporator core temperature around 35 -45 degrees. Any colder will cause icing.

fyi - an evaporator icing up can cause similar condition to what you are describing.

frosty

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