LX450 Air Conditioning Problem (1 Viewer)

[brtn540]

I went to a buddies body shop who has an A/C machine to refill the refridgerant. He tested the system and it showed no signs of leaks. When I left the shop the A/C was blowing ice cold but by the time I got home the A/C was not working and the system was blowing warm air. If the system isn't leaking what could be causing the A/C not to work if it was working when I left the shop and for about 45 minutes afterwards??? I searched for others with this issue but couldn't find anything.

Thanks in advance for your responses

Steve

 

[mingles]

Now that it has been sitting a while with the truck off, will it work again? If so, perhaps your evaporator coil is freezing up. For whatever reason (dirty fins, poor air flow, etc.) there may not be enough airflow across the coils and they iced up. At some point the air out the vents will go warm until the system is shut off and the ice melts off the evaporator.

 

[brtn540]

Now that it has been sitting a while with the truck off, will it work again? If so, perhaps your evaporator coil is freezing up. For whatever reason (dirty fins, poor air flow, etc.) there may not be enough airflow across the coils and they iced up. At some point the air out the vents will go warm until the system is shut off and the ice melts off the evaporator.

No I've tried it twice now since the trucks been off for 2 to 4 hours and nothing but warm air blowing out when the A/C is on.

 

[kruisinkid]

when it fades like that, its usually the expansion valve, which is attached to the outside of the evap core. my a/c all of a sudden went from fine to zero cooled air more or less over night. so ive been reading a lot about a/c issues is my point. im probably going to pull my evap and clean it thoroughly and change out the expansion valve.

 

[Kaveeks]

are you seeing any bubbles in the sight glass? double check your heater control valve to make sure it's closed?

 

[inkpot]

Is the a/c belt still on the pulleys and does the compressor actually rotate when turned ON

 

[brtn540]

Is the a/c belt still on the pulleys and does the compressor actually rotate when turned ON

looks likes the compressor is NOT engaging when the A/C is turned on. Does that mean there's low pressure on the high or low side and won't allow the clutch to engage?

 

[brtn540]

are you seeing any bubbles in the sight glass? double check your heater control valve to make sure it's closed?

No bubbles in the sight glass what so ever

 

[landtank]

sounds like you have a leak in the system.

 

[1972FJ55]

Do you have gauges so we could know what the static pressure is in the system? If the compressor isn't engaged, then something is signaling it to shut off, either the control head or the pressure switch.

 

[ZackR]

Sounds like a problem with the expansion valve, a leak in the system or air/moisture in the system.

 

[mod5csi]

Check the schraeder valves. Debris may have gotten in there. Leaks can be caused by just checking the system at a buddy's shop.

 

[bajaphile]

I've yet to have an AC problem, but the FSM outlines a nice procedure for checking the system.

 

[brtn540]

I'm going to see if I can find some pressure gauges and check the pressure on the low and high side next. Will follow up with my findings ASAP.
Thanks for all the great ideas.

 

[RiverCityDave]

I've yet to have an AC problem, but the FSM outlines a nice procedure for checking the system.

This right here ^

 

[stu8319]

I had a similar problem. The AC would work from time to time, but it was completely at random. Ended up being expansion valve, thermistor, and something else, I can't remember. Like others have said, I would check the expansion valve.

 

[brtn540]

I was able to check the low side pressure and there was none. I tried to override the compressor to get it to engage but was not successful. Is my next step to tear apart the dash and take out the core and check the expansion valve?

 

[kruisinkid]

As i said, from what i have read this week, you have the usual symptom of a failed expansion valve. Take it back to your friends shop to have the system evacuated and then pull the evaporator, clean the hell out of it, replace expansion valve and its orings, and replace the drier/accumulator if you dont think its been replaced in yhe last 5 or so years or unknown time. Its another $18 on amazon for then denso. Its right behind the bumper. Couldnt be an easier piece of mind thing

edit....also might be worth replacing the thermistor in the evap unit while you have it out. though i havent been able to find a good part number for it except the 40th annvy version.

 

[1972FJ55]

I was able to check the low side pressure and there was none. I tried to override the compressor to get it to engage but was not successful. Is my next step to tear apart the dash and take out the core and check the expansion valve?

Massive leak...there should be oil residue from the place(s) it's leaking.

 

[kruisinkid]

I went to a buddies body shop who has an A/C machine to refill the refridgerant. He tested the system and it showed no signs of leaks. When I left the shop the A/C was blowing ice cold but by the time I got home the A/C was not working and the system was blowing warm air. If the system isn't leaking what could be causing the A/C not to work if it was working when I left the shop and for about 45 minutes afterwards??? I searched for others with this issue but couldn't find anything.

Thanks in advance for your responses

Steve

going back a bit, what was the system doing before you took it to your buddies shop? was it doing the same blows cold for a bit, then warm? come back the next day and able to repeat the problem? if cold air comes back at any point after anytime downtime, id say expansion valve. if the cold air is gone for good and the clutch is not spinning when the system comes on, that could be a few different things.