a/c troubleshooting, a/c tech screwed me

[di_rosa]

well i changed the receiver drier, the compressor, and the expansion valve, and all the seals, then took my supe to get professionally serviced. well i told the guy that i only needed an extra 10cc/0.4oz of oil (which is what the TSRM calls for when installing new receiver/drier) added to the system since i replaced the reciever/drier, but the guy added 2 oz's of oil!

anyways, after he vacuumed the system for 45 minutes, and filled and leak tested, i have no cold air.........it is MILDLY cool when i'm cruising above 3k, but otherwise NOT DAMN COLD.

so my question is, is it before of too much oil, and if so, how do i fix?

or is it because of something else. i checked the low-side pressure (got some gauges) and it reads about 30psi. i also grabbed the lines on the compressor, one is cold, one is hot. i checked the lines going to the evaporator, one is cold, other is somewhat warm (hard to tell, there's a cover on it).

any suggestions please????

thanks

 

[808mkiiisupra]

idk to me ive always added 2.0ozs of oil all the time for common quick recharges...(unless a special case) how much freon gas did they actually put?

 

[suprabad]

It sounds to me like you don't have enough refrigerent in it, I don't think the 2oz's of oil would cause it not to be cold if everything else is in working order. I'd also have a look at the dual pressure switch.

 

[di_rosa]

really? i read that too much oil will hinder the cooling. but ok, i'll go and slap on some gauges and find out.

from what he said, he said he added about 1.7lbs

what exactly am i looking at with the dual pressure switch? i know the compressor is turning on because i can see the clutch start moving.

 

[808mkiiisupra]

a very "quick" check to see if you got enough freon is to check out the sight glass at normal operating temperature. if its clear then theres enough freon...if theres like air bubbles there isnt enough. check to see if he has dye inside of the system that way you can spot a leak somewhere too...hth

 

[figgie]

650 grams of R-134a is the updated qty that Toyota released in the TSRB for retrofitting the supra.

not 651 grams or 649 grams.

 

[di_rosa]

no sight glass, the new receiver/drier doesn't come with one, it's blacked out

 

[808mkiiisupra]

wat??? it should have one. i dont know otherwise then. i guess you have to hook up the guages then

 

[di_rosa]

650 grams of R-134a is the updated qty that Toyota released in the TSRB for retrofitting the supra.

not 651 grams or 649 grams.

so you're saying i have too much refrigerant in my system? that the extra oil has nothing to do with it?

 

[boostaddict]

to little refrigerant would cause freeze up and kick it off too much refrigerant would cause it to not be cold what was the air temp outside when you had the guages hooked to it and was the car running when you checked the pressure? do you have the high side pressure?
air temp/lowside psi/highside psi
70-80 / 16-29 / 115-200
80-90 / 19-39 / 140-235
90-100 / 25-43 / 165-270
100-110 / 37-51 / 210-310

 

[jetjock]

i checked the low-side pressure... and it reads about 30psi

 

[di_rosa]

car was running at night when i checked the low side, around 77*F, so pretty close to your chart there.

nah, my friend has my gauges right now, i'll be grabbing them shortly.


but if the line going into the evaporator is cold, shouldn't that mean there is a problem behind the dash with either the expansion valve or possibly some vent flapper problems? does the vent flapper move when you turn on the a/c? cause i can't hear it move

 

[jetjock]

I would certainly hope the engine was running when you saw 30 psi because if it was off I seriously doubt you'd even care the AC isn't working. In that statement also lies some insight into your problem...

 

[di_rosa]

care to share with the class?........................please

 

[jetjock]

I see by your edit you may be on the right track.

All refrigerants have a certain pressure/temperature relationship. It's what makes them refrigerants in the first place. For your suction line to be at 30 psi means the refrigerant's temperature in it (for HFC-134a) must be 35 degrees. Sounds cold to me...

 

[di_rosa]

ok, so you're referring to the vent flappers behind the dash.

well what's weird is i heard them "buzzing" when i pressed the buttons with my old climate control unit, but i switched to the 89+ style, and now i don't hear it. i was under the impression that they were both compatible?

 

[jetjock]

Supposed to be but I wouldn't know for sure since I have what came in the car. The air mix damper is what you want to check. It blocks the heater core in varying degrees based on temp setting.

Easiest way to check air mix and blend dampers is to put the system in auto and starting from 65 F raise the temp all the way up and back down again. Generally speaking air flow should be from the center vents when the temp setting is low and from the floor vents when high. Air temperature should follow. Fan speed should be lowest when temp setting matches ambient and increase as you move further away on either side of it.

With the AC on max, fast idle, and fan on medium you should be seeing a center vent temp of roughly 42 F on a 90 F day. That's with R-12 though. You won't see 134 in my car. Not that it doesn't work, just that I have a lot of R-12 sitting around.

 

[di_rosa]

yeah, alright, well i've been going throw some wiring diagrams seeing what to check and what to jump, and i'm tired. i'm just gonna slap in my old climate control unit tomorrow and see what happens.

thanks for the help everyone, i'll update it shortly hopefully with good news.