Why does my AC cool for about 20min and then just blows normal air

JOSEPHNSICILIMA

MEMBER
1997 TOYOTA LANDCRUISER
340,000 MILES

The mechanic changed the compressor because the one before had a leak he also changed the drier(accumulator) and the expansion valve now the ac cools well for 20min after the car came from being parked a few hours, once you use it for 20 to 25 min it blows of normal air you have to switch the car off or the ac off for an hours or so for it to cools well for the 20min.

5 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

System is icing up. You need to have him re check the system pressures to find the problem

Roy

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Thursday, September 6th, 2012 AT 11:44 AM

KHLOW2008

MECHANIC
41,814 POSTS

Try backing off the temperature to higher than minimum to see if problem persists. Keeping temperature at minimum coldness can result in frosting/icing of the evaporator coil when there are fresh air leakages into the cabin.

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Thursday, September 6th, 2012 AT 11:47 AM

JOSEPHNSICILIMA

MEMBER
2 POSTS

The mechnic changed the expansion valve there is a difference now it can go t0 40mins then blows normal air with decrease capacity of blowing after 40min, the other difference before the passanger and middle ac part were not as strong in cooling then the driver ac part now the cooling strength is similiar. Now if fresh air is leaking in the evaporator can it be sealed and how can we know if there is a leakage of fresh air into the evaporator?.I am also thinking can the replaced compressor be to powerfull for the evaporator that it makes if frost? I will work on telling him to check the pressure maybe its not adequate and also could the system have not enough oil? Or excess oil?

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Friday, September 7th, 2012 AT 7:42 AM

KHLOW2008

MECHANIC
41,814 POSTS

Ensure the vent for fresh air is set at recirculating. Check window glasses for proper sealing. Ensure the firewall grommets and wireharness holes are properly sealed.

The decreased air flow confirms the cooling coil is icing up.

If the thermosensor at cooling coil is not positioned correctly, the cooling coil would be iced up before the control unit is told to cut off. A faulty thermosensor would result in that also.

Did you try setting the temperature to a higher setting? I would never set my temperature at minimum when running for long distances.

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Friday, September 7th, 2012 AT 8:28 AM

ATY

MEMBER
1 POST

It could be one of this, thermoster not in the prober position, or the equalization tube for the EX valve not fitted on clean serface, as the technician have change it, I would recomend to start the vehicle and the AC at the 3rd speed and opne the doors get the air recycl from out the vehicle leave it runing for about 30 minet and see if it does it, then you need to check the EX valve and it is inside the evao box