Automotive Air Conditioning Information Forum

I'm in Phoenix, Arizona; I replaced the compressor in my 1988 Mazda B2200 truck almost 2 years ago with a brand-new unit from AMA here, new drier, high pressure line flush, etc. The system is still R-12.

I've been spending a fair amount of time this summer up north, so the truck has not been driven much. The AC seems to be working less well than in the past, and there are some bubbles in the sight glass, so it seems that I've lost a little refrigerant. I did not add dye (dummy = me) when I did the compressor job, but I do have soap bubbles and an electronic halogen detector. Twice now I have looked for leaks, and haven't been able to detect any leak around the compressor front or back or caps, the lines and crimps, or connections. I didn't get any beeping from the sniffer at the condenser area either. The only place I get any positive leak detection is out the air vents and maybe out the evaporator condensate drain.

So today I pulled off the bottom of the evaporator case (the evaporator was replaced by a new one from AMA back in 2002) and saw dust build up on the "blower side" of the evaporator, but no oily residue indicative of a leak. I sniffed with the detector at the expansion valve connections, the evaporator coils themselves, etc., really could not pinpoint any leaks. I washed off the dust with water and a toothbrush, tried soap solution, still could not find "smoking gun" of a leak. So I reattached the evaporator case bottom and took on a short drive of 4 miles with outside temperature about 102 °F, lowest vent temperature was 46 °F. When I returned I did get some positive from the air vents.

So my thoughts are (1) maybe I've been spoiled by driving a Frontier truck that has better AC up in cooler climates, and I "forget" what Phoenix summer driving is really like, especially on short drives. Or (2) maybe I should take to my mechanic and have him weigh the remaining R-12 and add dye/let him check for source of leak.

I don't really feel like replacing the evaporator and (factory) expansion valve just on what I've found so far....

Can you clean the evap core? May improve performance with proper air flow.

Tim wrote:Can you clean the evap core? May improve performance with proper air flow.

I did clean the evaporator off off somewhat to restore air flow; was OK to take out to dinner at 7pm. but still like 108 °F then, and my garage was 120 °F. I didn't measure the output temperature, think I'll let my mechanic take a look at it to help me determine point of leakage, need a second pair of eyes on this one. This system used to work real well, and reach cold enough temperatures to cycle the compressor, unless the truck had been parked in the sun.

I was out on a bike ride tonight when it was 106. Got to do my best to stay in shape for the transplant if I get lucky enough to find a donor.

I took the B2200 in to the mechanic today, we'll see. I rode my bicycle home 5 miles (replaced flat tube before I left home), vacuumed my above-ground pool, cut off 3 tree branches using a pruning blade attached to my swimming pool pole. So I'm tired and hot. Think that's why I'm leaning towards letting the mechanic do whatever is necessary when I hear from him...

I got rid of my trees last year. So old would crack every monsoon.

I want a pool. But will wait until I move to Prescott.

Above-ground pool (mine is 15 feet x 4 feet, real sand filter and real pump) cost me $1100 back in 2000; compare to in-ground pool costing like $60K, but home with a pool only is like $2K additional value. Above ground is simpler and less expensive to maintain as well; many people consider these "too redneck", but they do the full function, and no one has to sacrifice the entire yard, or to have it filled or decked over some day.

Anyway: the mechanic retrieved the R-12, found it like 6 to 8 oz. low. So he added UV dye and the additional R-12, so we'll watch it for performance and/or leaks.

Had an above ground when I was a kid.

OK, found my UV light and goggles, put in new batteries (always store stuff with batteries out because of corrosion, happens especially in the southwest heat). I had driven like 15 miles with AC on so I spent 7am to 8:30am this morning looking for leaks from the UV dye, didn't see ANYTHING !!! I checked the condenser too through the grill and from underneath, nothing. Nothing at the compressor or service valves either (double-checked caps and high pressure relief valve with bubble solution). I even pulled off the lower evaporator cover again after not seeing any dye in the condensate drain, and no leaks in there either !!!

Anyway, while the silicone adhesive for the foam was setting, I picked up a full trash bag of mesquite pods, twigs from the mesquite, and of course the unavoidable rocks, had to pull some out as could hardly lift the bag even after, and trash was this morning, so beat that by 10 minutes. Then I made a marker for my daughter's now-deceased cat from a piece of wood and the drill press, fixed the front brakes and front shift adjustment on my bicycle, and also drilled/ran a sheet metal screw into the bottom of the kickstand to essentially lengthen the kickstand by 3/8-inch so the bike wouldn't fall over anymore.

Anyway, no bubbles in the sight glass, so I'll do what the mechanic said: monitor it, and if the leak reoccurs he and I will both search for leaks. So after this "break", I get to put the lower evaporator cover back on (I glued some foam insulation onto the one end clamp), that garage will be fun in mid-day, that's for sure; with 110F and humid, not so much fun here in the summer....

GM Tech wrote: Comment from a different post: Fix is to discharge, recover and weigh to prove loss of refrigerant, then find and fix your leak, then recharge to factory spec and be cool on both sides...

EXACTLY the strategy I'm now using on my own 1988 B2200.

The mechanic recovered and weighted the refrigerant, showed it was low at least 6 oz., and he added UV dye. So if the refrigerant level drops again, UV dye should be be able to seen and such component repaired/replaced.