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Another A/C problem thread

S

Steve93mustanglx

Diesel fanatic!
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Midlothian, VA
Hey folks,

Got my starter on and all I can say is WOW. That's how a starter is supposed to work? Sweet! Never started so fast... that is a great thing.

So... of course now the A/C is taking a dump. I have rear A/C, last year replaced compressor, last week replaced orifice tube and accumulator. My buddy has a set of professional gauges and my R-134 was spot on pressure wise. Pulled vacuum for an hour before filling with freon.

Here is/are my problem(s):

* Compressor kicks in when A/C is switched on (good).
* A/C blows hot air (not good). Initially, blew cold(er) in rear, now both are hot air only.
* A/C light on switch is on, then off whenever it wants (???)
* Recirculation button light never on.
* Accumulator does not sweat. Some sweat on orifice area, not much.
* Sometimes when fan is on highest setting, my pyro gauge flutters below the zero level. WTF?
* Other wierd stuff- no cruise control, sometimes fan will not blow on highest setting, fuel guage wont go over 1/2, oil pressure gauge only goes to zero when really at 40 or more psi, blower motor will not come on until I add an auxiliary ground, and back in the winter the heat wouldnt always switch to different positions when switch was moved.

Could the flaps be stuck? Do dual A/C units have 2 orifice tubes? Ideas? ITS HOT OUTSIDE!

Thanks!
 
Could be a bad/fried PMD? ):h











Actualy I was thinking pluged up orfice tube. Did you flush the system out? I now recomend a VOV instead of the orfice tube, world of difference.
 
The condenser is very hard to flush properly. Surely you had the OT out while flushing condenser. Did it have junk built up on it?
 
If you read the other AC thread, the dual ac only have orifice in the front.

I have the same symptoms as yours for about 2 years, finally, I gave up and replace the compressor and all that have to be replaced. I charged it up for a while until both the front and the back are hot. Then I just put it in the shop specializes in AC and sold the AC parts also. Now it is good. If you want to fix it, do it now before it gets cold again.

Yours and mine are practically the same.
 
Very posibile OT is pluged, but Im definately not the expert maybe WW or Kenny can help more.
I had to flush mine maybe 10 times just to get rid of the dye that was in it and that was just the evap, took just over a gallon to flush it. I put all new condenser,compressor, and dryer on it
 
I read them, and at least one I read seemed to lead me to think there might be 2.

I've replaced the compressor, accumulator, and orifice tube... and lots of freon in the process...
 
condenser... sigh... i sure hope not.

Anyone think my wierd switch/instrumentation issues could be indicative of an electrical issue related to this??
 
I am not familiar with how the newer burbs are setup. ON the older ones the second orifice is in the back by where the bend goes into the truck.
 
On a somewhat unrelated note, I replaced my high-side service port today. It had a slow leak that got worse after I tried to clean it out. Pulled new O/T again today- clean as a whistle.

As a side note- rear A/C has an expansion valve as opposed to #2 OT... at least according to Napa.

Gonna pull another vacuum tomorrow after a nitrogen purge. Then go for the fill. Guess we'll see.
 
High side port almost 99% of the time leaks when f'ed with. There is a special socket to remove it. You can do it with an adjustable but you could easily distort it.
 
Acesneights1 said:
High side port almost 99% of the time leaks when f'ed with. There is a special socket to remove it. You can do it with an adjustable but you could easily distort it.
Click to expand...

1995 was a FUBAR year for AC. Not only a unreliable HVAC control head: The factory hoses for my Yukon, 350 gas, did not have a serviceable high side port. The GM dealer replacement hoses I got did have a replaceable high side port. And I got the hose set due to the high side valve leaking...
 
Steve93mustanglx said:
Hey folks,

Got my starter on and all I can say is WOW. That's how a starter is supposed to work? Sweet! Never started so fast... that is a great thing.

So... of course now the A/C is taking a dump. I have rear A/C, last year replaced compressor, last week replaced orifice tube and accumulator. My buddy has a set of professional gauges and my R-134 was spot on pressure wise. Pulled vacuum for an hour before filling with freon.

Here is/are my problem(s):

* Compressor kicks in when A/C is switched on (good).
* A/C blows hot air (not good). Initially, blew cold(er) in rear, now both are hot air only.
* A/C light on switch is on, then off whenever it wants (???)
* Recirculation button light never on.
* Accumulator does not sweat. Some sweat on orifice area, not much.
* Sometimes when fan is on highest setting, my pyro gauge flutters below the zero level. WTF?
* Other wierd stuff- no cruise control, sometimes fan will not blow on highest setting, fuel guage wont go over 1/2, oil pressure gauge only goes to zero when really at 40 or more psi, blower motor will not come on until I add an auxiliary ground, and back in the winter the heat wouldnt always switch to different positions when switch was moved.

Could the flaps be stuck? Do dual A/C units have 2 orifice tubes? Ideas? ITS HOT OUTSIDE!

Thanks!
Click to expand...

You have several problems.

Start with the blower motor connector under the dash: a short distance from the blower motor spade terminals a connector wrapped in foam - remove the glove box to get there. If this connector is burned up, it can look melted from the outside, cut it out and repair the wires. Then remove and throw away the blower motor as it is shorting out, drawing too much current, and will burn up the connection again left in place. Trace the ground for the blower motor till you hit metal if the connector is ok. Common for the blower motor to short out and still run taking connectors and ground connections out by meltdown and burn up.

As suggested from another reply you may have ground issues. I would start with the gauge fuse by checking it's contacts for corrosion and then check all the grounds and positive battery posts. Check = take it apart. Also you can check for voltage with the engine running: frame to fender, engine to frame, engine to fender, engine to neg battery terminal, positive battery terminal to alternator charging terminal... Anything measuring near or over 0.5 volts needs work.

Ground under transmission dipstick bolt on rear of engine should be checked. ALDL ground just above (1" away) the connector on lower dash if equipped for your year needs to be checked.

Other grounds ... look for them and other members can say where they are.

A Pyro is a parakeet in a coal mine. Bad ground or positive voltage causing a brown out aka under volt to it will cause the display sweep to malfunction.

After checking grounds...

Have both batteries tested. A shorted cell will cause the alternator to generate extreme AC noise attempting to charge the shorted battery and still have a brownout for electrical stuff.

Test the alternator as well for the same reason just to rule it out.

HVAC control head, the thingy with the AC and recurc button, may be bad. This will slam the heat to full on, not turn on the AC compressor, and other weird system operation despite what the controls are set to. Intermittent and even the dealer has trouble pinning this down. I traced the AC clutch wire back to the control head before condemning it and had the dealer fix, replace, it just in case it wasn't. It was the control head. Failed about every 2 years.

Accumulator does not sweat - So what? This can take special conditions like low fan speed and full lock up engine fan to happen. If your charge is good, no leaks, pressures ok, engine fan clutch tested, and radiator/condenser clean you have other issues. Likely full fan speed and heater on max heat position from control head failure keeping the accumulator from sweating. (Failure can be a bad ground.)

A stuck open expansion valve could cause a lack of cooling. Oddly GM used one on the rear AC making this system a goat F&^%! The following applies to 1995.

http://www.alldata.com/service_provider/techrx/2001/20010703f.html

:eek:
 
yup- mine went from leaking to full blown gusher. Adjustable did the job, but you have to really be careful as it will try to round off easily.

I also fixed the fuel and oil pressure gauges by removing the cluster and reclocking the needles. Easy as hell and it works. Wish I had done this 3 years ago. So... not sure about the ground problem now.
 
UPDATE: tonight buddy came by and evac'd system and weighed in the correct 4.0 lbs r-134a charge (used scale). Idling, pressure on high side was 220, low was 50. Idling at 1200rpm, high went to 250, 40 on low. The cabin temps only dropped to 65ish at idle, roughly 58 driving. Ambient temps are upper 80s at night.

The receiver sweats like a beyotch and front and rear units are condensating.

EDIT: The line to the TXV is balls hot, coming out is cold. Also, the low pressure switch is working- you could hear it when system was pressurized.

EDIT #2: Batts and alt just tested lasy week due to (now replaced) starter. Grounds on my batts and chassis are beyond clean and checked 30+ times in past month alone!

Thoughts?
 
Last edited:
That low side seems high. I would guess it's overcharged or the expan valve or Orifice is not working properly. 4lbs sounds a little high. Is that what the sticker said ? How are you measuring cabin temp ? You have to have it on recirc and the windows closed with thermo in one of the center vents.
 
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