A/C it works fine for the first 15 minutes or thereabouts and then starts to blow warm?

MAUFOS

MEMBER
2008 MITSUBISHI LANCER
2.0L
4 CYL
2WD
AUTOMATIC
175,000 MILES

Hello, I have the car listed above Fortis (ALA Lancer GTS in the States). When I turn on my A/C it works fine for the first 15 minutes or thereabouts and then starts to blow warm. Things I've noticed, my condenser and radiator fans seem to run at full speed from the time I turn the A/C on. The compressor and condenser fan cycles on and off at first but then runs constantly when the A/C starts getting warm. The car doesn't seem to overheat as my engine temperature gauge stays in the middle, but my ambient temperature reading starts to increase. Also, sometimes with the A/C on, when coming to a stop, I can feel the engine revs drop briefly as if it's about to cut out but then it quickly returns to normal, this does not happen when driving with the A/C off. Things done to vehicle recently, new fans, compressor changed (second hand), seals changed, A/C gassed. Thoughts?

9 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,356 POSTS

It sounds like the system is overcharged or the compressor is not working correctly but to be sure we need to see the high and low side pressure readings.

These guides and videos will help us see what's going on:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

and

https://youtu.be/4EqdrBVb0sY?si=NM4brO2WJHUWnfhz

Please go over these guides and get back to us.

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Tuesday, January 9th, 2024 AT 9:10 AM

MAUFOS

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5 POSTS

Hello, many thanks for your response, I'm not doing the work myself, but the levels were checked by the tech previously and they were fine according to him, afterwards the car was driven for about 15-20 minutes and the problem surfaced again. When the car is parked for a few hours or overnight and then used, the A/C blows fine again for a few minutes before getting warm again.

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Wednesday, January 10th, 2024 AT 5:58 AM

KEN L

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48,356 POSTS

When you turn the A/C system on can you hear the radiator cooling fan run?

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Wednesday, January 10th, 2024 AT 4:31 PM

MAUFOS

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5 POSTS

Yes, as mentioned initially, the fans run as soon as the A/C is turned on, in fact it sounds as if they are running full speed.

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Thursday, January 11th, 2024 AT 7:35 AM

KEN L

MASTER CERTIFIED MECHANIC
48,356 POSTS

Okay, I had to double check, it sounds like the expansion valve needs to be replaced or the compressor seals are going bad. We need to have the system high and low side pressure readings while the system is not cooling to see what's going on.