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natureboy on Wed April 21, 2010 4:20 PM User is offlineView users profile

Year: 1999
Make: Dodge
Model: Caravan
Engine Size: 2.4
Refrigerant Type: 134A
Ambient Temp: 70F
Pressure Low: 10
Pressure High: 250
Country of Origin: United States

Hello all ! I'm toying with this mini-van and have the following information so far, and I'm praying somebody more knowledgeable than myself can shed some light!

System sticker under hood states capacity of 2.34 pounds of R134A
Found system empty - zero pressure on either side
Filled system with 12 oz 134A and 2 oz oil to sniff for leaks - sniffer found no leaks - hmmm...
Continued to fill to stated capacity with a total of 34 oz of 134A
Guages showed -6 low and 125 high at this point with no cooling in cabin - condenser fans both running strongly and evap fan on high
Experimented with more 134A - 12 oz more and pressures were 2 low and 200 high with negligable cooling
Added another 6 oz 134A to arrive at 10-12 low and 250 high at idle - and 3-5 and 280 high at 2000 engine RPM - negligable cooling and noticed an occasional condensation drip from (TXV?) block at firewall evap connection - high and low side piping had little temp difference
Being a scared conservative I stopped adding 134A at this point and took a drive on the highway - slightly better cooling out on the open road, but still close to ambient

Any ideas? I'm just a shade tree mechanic with basic knowledge of HVAC systems and have worked on Ford and GM systems using mostly what I've learned here!


GM Tech on Wed April 21, 2010 6:42 PM User is offline

I didn't hear a vacuum pump mentioned...air in the system will make system pressures high and hard to work with.

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

natureboy on Wed April 21, 2010 6:55 PM User is offlineView users profile

You are correct - no vacuum pump was used ...... I was running with the possible erroneous presumption that unless the system was opened up to the atmosphere in some way (other than a leak, which I viewed as being discharge only, maybe another error) there would be no air in the system and it would not require evacuating. Oops?


Chick on Wed April 21, 2010 10:40 PM User is offlineView users profile

I would change the drier and expansion valve while you're at it, here's a link to the parts 99 caravan 4cyl the parts are cheap enough... then pull a deep vacuum and add the correct amount of oil and refrigerant to the system.. If you don't flush the systrem 2 or 3 ounces of Pag 46 for the drier...

Email: Chick


Freedoms just another word for nothing left to lose

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