OT- auto A/C problem need help

[demarpaint]

Hi and thanks in advance,

I've always been able to repair cars, however this one has me bugged since A/C work is not my strong point.

The vehicle in question is an 88 Ford E-150 Van.


At an idle with a fully charged system, no leaks, no blockages etc. I have approx 60lb back pressure, 125lb on the high side. Ambient temp was about 75 degrees.

With engine running at cruising speed 44lb back pressure 225 high side.

At idle the A/C is warm at the cruise speed its blowing cold air. Van is running about 1,500 RPM A/C is cool, curb idle A/C blowing warm.

The compressor is operating and not making any weird sounds, the van doesn't over heat.

Any ideas??

Thanks
Frank D

 

[DaddyRabbit]

I don't know as to the method you're checking your system for being fully charged, I.e, OA +32degrees, weighing it in, sight glass, etc, etc. I can tell you if your condensor is dirty you'll suffer this quandary if you charge your system via OA method. I'd check to make sure your condensor is moving enough air. You said there's no blockages so that leaves out a blocked drier or an orfice/expansion tube....you'd see these on your low side. Blocked condensor or non-condensable will show up on your high side. Not too many options left.

[ QUOTE ]
Hi and thanks in advance,

I've always been able to repair cars, however this one has me bugged since A/C work is not my strong point.

The vehcile in question is an 88 Ford E-150 Van.


At an idle with a fully charged system, no leaks, no blockages etc. I have approx 60lb back pressure, 125lb on the high side. Ambient temp was about 75 degrees.

With engine running at cruising speed 44lb back pressure 225 high side.

At idle the A/C is warm at the cruise speed its blowing cold air. Van is running about 1,500 RPM A/C is cool, curb idle A/C blowing warm.

The compressor is operating and not making any weird sounds, the van doesn't over heat.

Any ideas??

Thanks
Frank D

[/ QUOTE ]

 

[Buffalobob]

Get a big hammer and knock the whole unit out. That way it will be easier to get the 460 CID into the engine bay.

95 black on Black Mustang - with delete AC. Had to special order the car just to get it without AC.

74 Vette 454 - cant have an AC unit restricting air flow around that big block.

Oh, I am sorry. you wanted the AC to actually work? I'm only good at making it not work.

 

[demarpaint]

Re: OT- auto A/C problem need help ATT Daddyrabbit

Daddyrabbit said: [ QUOTE ]
I don't know as to the method you're checking your system for being fully charged, I.e, OA +32degrees, weighing it in, sight glass, etc, etc. I can tell you if your condensor is dirty you'll suffer this quandary if you charge your system via OA method. I'd check to make sure your condensor is moving enough air. You said there's no blockages so that leaves out a blocked drier or an orfice/expansion tube....you'd see these on your low side. Blocked condensor or non-condensable will show up on your high side. Not too many options left.


[/ QUOTE ]

The evaporator had to be replaced original in 1988 van all freon leaked out, checked with dye and sniffer determined it was bad. Upon removal saw it was leaking at a seam.
Replaced part evacuated system held vacuum for 4 hrs. Charged with Freon, weighed charge at 3.5lb, as per shop man, also monitored with the gauges.
Hope this helps, was thinking fan clutch (not cooling condensor enough) could be bad, but the high pressure reading is what is messing me up. I don't want to throw parts at it, its not overheating, leading me to believe the fan clutch is good, but I didn't check it.



Thanks
Frank D

PS OA method???????? Not sure what you mean.......thanks, enjoy the holiday weekend!!!!!!!!!!

 

[DaddyRabbit]

Re: OT- auto A/C problem need help ATT Daddyrabbit

That yr would require R-12 unless you replaced it w/R-134A. If your clutch fan were bad your head pressure would be "off the hook" while it was idling. Well, you could always dump the system and recharge again. Make sure your condensors clean.Oh yeah...OA=Outside Air

 

[demarpaint]

Re: OT- auto A/C problem need help ATT Daddyrabbit

My father in law was an A/C repair man now retired (this has him scratching his head), and had about 15 LB of Freon. Thats what we used to charge it up.

I am now thinking the idle speed might be just a little too low. 550 RPM while at idle w/A/C running. Not sure if being a 5 speed stick matters with the idle, I doubt it though.

Thanks
Frank D

 

[DaddyRabbit]

Re: OT- auto A/C problem need help ATT Daddyrabbit

So I'm assuming your low side rises to over 45deg on the low side at idle? I dunno. At idle you're not seeing any freezing on your liquid line whatsoever? What's a stick idle at 600 rpm? Hmm, a 5 speed van?!?!

 

[demarpaint]

Re: OT- auto A/C problem need help ATT Daddyrabbit

Van idles around 550-600 RPM EFI. Back pressure on gauges is 60lb and 125lb on the high side. Temp at the A/C vent is about 58 degrees when its about 75 outside.

At a fast idle 1500 -2000 RPM Back pressure is 44 lb and 225lb on the high side. This is where is should be at a curb idle. At 1500-2000 rpm temperature at the A/C register is about 44 degrees.

Factory 5 speed van, I ordered it new this way. Just like driving stick over an automatic /ubbthreads/images/graemlins/smile.gif

Frank D