Recently "completed" an almost complete AC replacement on my friend's 1988 CV. Replaced the compressor (it was shot), condenser, receiver/dryer and orifice tube. Vacuumed down the system, for almost an hour and it was fine. Found a leak at the pressure switch so I checked and replaced the o-ring and replaced with a new switch. Also did ALL the o-rings no matter if they needed it or not. Next day, the low side was reading about 25 after I had it up to 35-40 and temps down to about 40 the day before. So, yes - LEAK! Had dye in the system and found no leaks. Even used a "sniffer" and again, no leaks. Thinking the evaporator may have an issue so unless a rubber hose is leaking (not according to the "sniffer") it is the only other place to have an issue. Wonder if the evaporator can be removed completely from under the hood (never did one on this year and model)? Any other overall ideas?
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Last edited by friskyfrankie; 09-13-2023, 11:13 PM.What I Own: 1993 Mercury Grand Marquis GS
What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo -
Other than the schrader valves, I can't think of anything you haven't already touched on.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
Originally posted by gadget73Originally posted by dmccaig -
New valve on the low side but not the high side. Guess even new stuff can be defective but dye and sniffer did not indicate an issue. Just for laughs I need to remove the caps, on both valves and retest. This is a tough one...if they don't pan out, a closer look at the evaporator will probably be next. May have to wait a bit since lately I'm doing what I dislike most - living in doctor's offices! .What I Own: 1993 Mercury Grand Marquis GS
What I Help Maintain: 1996 CV / 1988 CV / 1988 TempoComment
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I'm guessing there wasn't a huge outdoor temp swing when you tested the pressures?
I'd let it keep leaking at this point and maybe it will make itself more obvious.1990 Country Squire - weekend cruiser, next project
1988 Crown Vic LTD Wagon - waiting in the wings
GMN Box Panther History
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About 90 plus outside temp and around 60 in the car (in a garage, however). Some folks may think that is good but after the repair and also after the "first leak" (from the pressure switch) I had it down to around 40!Originally posted by Tiggie View PostWhat I Own: 1993 Mercury Grand Marquis GS
What I Help Maintain: 1996 CV / 1988 CV / 1988 TempoComment
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stick the sniffer in the dash vents, if its leaky it should pick it up from there. Another clue, if you have dye in it you may find it at the evaporator drain if the evap is leaky.
Fittings are highly suspect, have had a lot of issues with them on various things.86 Lincoln Town Car (Galactica).
5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley
91 Lincoln Mark VII LSC grandpa spec white and cranberry
1984 Lincoln Continental TurboDiesel - rolls coal
Originally posted by phayzer5
I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousersComment
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Excellent info. Will be trying to get to it by next Tuesday?What I Own: 1993 Mercury Grand Marquis GS
What I Help Maintain: 1996 CV / 1988 CV / 1988 TempoComment
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Good luck.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
Originally posted by gadget73Originally posted by dmccaigComment
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Thanks - should be "fun"!Originally posted by sly View PostWhat I Own: 1993 Mercury Grand Marquis GS
What I Help Maintain: 1996 CV / 1988 CV / 1988 TempoComment
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