86 a/c issue and wire identification
Thread Starter
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From: Eastern Shore, MD
Out of curiosity, ran a test wire to the compressor off the pos terminal and sure enough a hard click. So, what should I investigate with this now known information?
Last edited by chakka; Jul 23, 2024 at 09:31 AM.
Thread Starter
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From: Eastern Shore, MD
Getting back on the lack of a/c. Did an evac & refill (860 grams r-134), to make sure that was correct. Started the car, jumped from point under the hood directly to engage compressor directly. It engaged, but no cold air. Going to check low/high side pressures over the weekend. Now wondering if it’s the compressor as well as the hvac relay?
Last edited by chakka; Aug 16, 2024 at 09:01 AM.
Thread Starter
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From: Eastern Shore, MD
Doing some reading in here, does it take up to 20 min for an evacuated/refilled system to allow the air to start getting cold the first time it's run after this is done? I only ran it for 3-4 min with warm air coming out.
Team Owner
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From: Philly PA
run the system and while thats happening,
put your hand on the expansion valve,
if it s not cold then its probably plugged,
NEXT look at the glass window and see if their is movement of the refrigerant.
NEXT verify that the compressor clutch is engaged and turning.
put your hand on the expansion valve,
if it s not cold then its probably plugged,
NEXT look at the glass window and see if their is movement of the refrigerant.
NEXT verify that the compressor clutch is engaged and turning.
Thread Starter
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From: Eastern Shore, MD
-Looked at glass window and there was movement of refridgerant
-Hand on expansion valve(car running/clutch engaged) and not cold(no noticeable change from temp prior to starting car)
Team Owner
Joined: May 2004
Posts: 31,279
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From: Philly PA
OK it sounds like the expansion valve is plugged,
so you might be ready to do a proper overhaul of your refrigerant system ,
this should include a new compressor and both of the flex lines,
a full system flush with new green O rings being installed after the flush.
new drier and expansion valve.
If possible use R12 and mineral oil .
NOTE if the oil in your system is not clear or lite tan ,
but maybe a rusty color,
then it indicates its been mixed with some other incompatible oil
so you might be ready to do a proper overhaul of your refrigerant system ,
this should include a new compressor and both of the flex lines,
a full system flush with new green O rings being installed after the flush.
new drier and expansion valve.
If possible use R12 and mineral oil .
NOTE if the oil in your system is not clear or lite tan ,
but maybe a rusty color,
then it indicates its been mixed with some other incompatible oil
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Posts: 1,979
Likes: 186
so you might be ready to do a proper overhaul of your refrigerant system ,
this should include a new compressor and both of the flex lines,
a full system flush with new green O rings being installed after the flush.
new drier and expansion valve.
If possible use R12 and mineral oil .
NOTE if the oil in your system is not clear or lite tan ,
but maybe a rusty color,
then it indicates its been mixed with some other incompatible oil
this should include a new compressor and both of the flex lines,
a full system flush with new green O rings being installed after the flush.
new drier and expansion valve.
If possible use R12 and mineral oil .
NOTE if the oil in your system is not clear or lite tan ,
but maybe a rusty color,
then it indicates its been mixed with some other incompatible oil
for cars at 30+ years old, it’s time. It also provides relief that the AC work is finally over, working at its best.
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Thread Starter
Rennlist Member
Joined: Dec 2009
Posts: 752
Likes: 127
From: Eastern Shore, MD
Went ahead and removed HVAC controller and wired in (via Dwayne's write-up) a new relay and added an inline 3amp fuse by the anti-freeze switch. So, now the clutch engages, via the a/c button(which it wasn't before).
Next is on to the vacuum system, since several of the settings don't operate, while waiting for new parts to arrive.
Compressor, receiver drier & expansion valve, heater control valve to be ordered.
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From: Grapevine, TX
What method are you using to weigh the mass of the charge you are putting in?
Thread Starter
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From: Eastern Shore, MD
that high side pressure seems quite low for a R134a system. I don't know what your ambient temp is, but I'd guess you should really be in the 250-300 range. Most R134a systems have a low/high cutoff switch with low cutoff point below ~27 and high cutoff above ~380. Based on your pressure numbers I'd say you're significantly under filled.
What method are you using to weigh the mass of the charge you are putting in?
What method are you using to weigh the mass of the charge you are putting in?
Thread Starter
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From: Eastern Shore, MD
Rennlist Member
Joined: Nov 2008
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From: Grapevine, TX
The high side will actually be controlled by the vapor pressure based on the temperature of the high side and having enough refrigerant in the system saturate the condenser. at only 105 psi U highly suspect you do not have enough in the system to have any significant quantity of liquid formed with the condenser.
the 43psi that you state on the low side would indicate that your compressor is doing a significant job of drawing the refrigerant out of the evaporator and you should be getting vent temps under 50F. but as you state you do not seem to be getting any appreciable cooling at the vents with that low side temperature it would indicate that you do not have sufficient liquid in the system to evaporate and cool the entire evaporator,
If your high side were low AND the low side were high I would agree that the compressor is likely inefficient, but as the low side appears to be within the expected range it appears to me to be more of a quantity issue than a mechanical issue.
For reference I ended up charging my 86.5 with rear air to 37 oz (1050 g) of R134a. Of course if you don't have rear air that would account for a lower volume.
the 43psi that you state on the low side would indicate that your compressor is doing a significant job of drawing the refrigerant out of the evaporator and you should be getting vent temps under 50F. but as you state you do not seem to be getting any appreciable cooling at the vents with that low side temperature it would indicate that you do not have sufficient liquid in the system to evaporate and cool the entire evaporator,
If your high side were low AND the low side were high I would agree that the compressor is likely inefficient, but as the low side appears to be within the expected range it appears to me to be more of a quantity issue than a mechanical issue.
For reference I ended up charging my 86.5 with rear air to 37 oz (1050 g) of R134a. Of course if you don't have rear air that would account for a lower volume.