Last summer I replaced the compressor, dryer, and expansion valve in my 300TD as well as o-rings at each of those places.

refilled with lubricant and R12 and all was good.

Now the AC is acting weird again. it takes about 10 min for the compressor to engage. If I feel the tube in front of the valve cover, it is uncomfortably hot.

last week I put a can of R12 in and the L.P. side went to 35 and held, but yesterday it was at 20. (That is when the compressor is on)

I see movement in the dryer watch glass.

When I scanned the system with a leak detector, I got nothing under the hood (tested joins at dryer, tubing to compressor, joints at compressor), but I did find a few blips inside the car. Mostly when I held the detector in front of the vents. Not alot though, just an occasional blip. When I removed the kick panel and put the sensor tip near the expansion valve I never really heard any blips.

This is bad isn't it?

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Could be the evaporator beginning to leak...if you get blip from the vents.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

Be sure your connections at the TxValve to the Evaporator are good...
did you make something to hold it steady while tightening those fittings ?
It is more likely a small leak in the evaporator.... pretty bad if it is...
taking the dash apart and replacing it I think is listed at 17 hours in the flat rate manual...
several threads about it...
Hope that is not the problem...
Did you call Tray at Carlisle Auto Air... given that you live in their town they might can help...

Thanks y'all.

I am afraid it is the evaporator. I used channel locks to hold the Xvalve in place when i installed it

I didn't get any reading from the connections at the valve.

I took it to Carlisle (the one on Huebner) last summer and they quoted me a price to replace the compressor and refill but the markup on the parts was really high, and they wouldn't let me bring in my own compressor. So for the same price, I was able to do it myself by buying a few tools and the parts.

For the evaporator, I think I might take it in to get it done. Esp since this car is the family car and we would need pretty quick turn around. I am going to cry when I get the bill I am sure..

Is there anything elseI should check before I take it to Carlisle?

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Is everything on the car except the evaporator in great shape ?
Get an estimate before committing .

I was not totally sure about about a leak inside the car. I closed up the windows overnight and left the electronic leak detector in the car. the following day I quickly opened the door and turned on the detector. It immediately alarmed. This lead me to the TX valve. It was a small leak at the valve. I hope you have a high quality detector. Searching for a leak in engine compartment without one is futile. I know this sounds like a backyard way of finding a leak but it worked. Good Luck.

Thanks topgun, how did you localize the leak to the expansion valve?

leathermang: yes, everything else should be in good shape.
Yesterday, took the car out and the AC worked - sometimes it takes about 10 min of driving before the compressor kicks in. Once that happens it gets cold (though not as cold as when I first repaired the system last summer.
Low pressure side remains steady at 20. Haven't check HP side yet.

Definately getting blips from the vents, if I stick the tip down into the vents. The most blips come from the far passenger side vent.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Hello Zeke, Knowing the leak was in the cabin, I probed the drivers side under dash until leak detector alarmed. Removing part of lower dash and driver side kick panel, led straight to TXV. Fortunately after replacing TXV no further leaks were found. I might be tempted to recheck the area near the TXV. Maybe the refrigerant is migrating up to the vent areas. I am not familiar with your model. Maybe there is a way to get to the evaporator compartment to test. On my car (560SEL) it was not feasible. It has an air bag where you would normally find a glove box.Good Luck.

Not familiar with your model, but could it be an electrical issue? Faulty Klima relay?

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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"Back off, man. I’m a scientist” ~ Peter Venkman

If it were not for the leak detector beeping I would be checking the switches and stuff which activate the compressor... and that still may need to be addressed ( 10 minutes is too long in Texas for the AC to turn on ) once the leak is fixed.