AC Cold for 30 mins and then not that cold anymore - Toyota Nation Forum : Toyota Car and Truck Forums

ruoknow · 08-24-2005, 01:22 AM

Avalon sub-forum is too slow for technical questions. It seems like technically more experienced people like to drive a camry

.

anyway, recently, my 96 avalon (90000 miles) developed a problem: the ac works very well at the beginning (blows cold air), but after about 30 mins, the air blown out is not that cold anymore (a little bit warm, but still lower than the temperature outside). At this time (not blowing cold), the AC switch is normal (not flashing). This sympton is very repeatable, no matter what speed i drive.

Anybody knows why?

ffpmlex · 08-24-2005, 01:38 AM

Many vehicles have a built in feature where the A/C compressor automatically disengages to take the load off the engine so that it doesn't overheat. Since it occurs only after driving for a while, this could indeed be your problem, but it is a built in safety feature and is considered normal. The only thing you can do if this is the case is to make sure the engine is getting cooled efficiently...make sure your coolant is topped off and in good condition...make sure no leaks are present...make sure your engine oil level and quality are OK.

Boostyle3VZ · 08-24-2005, 01:55 AM

expansion valve

ruoknow · 08-24-2005, 01:56 AM

Thanks ffpmlex.

when the car is doing that, the temperature gauge is quite normal.

Axel Kain · 08-24-2005, 02:05 AM

i agree with ffpmlex, make sure your your compressant is topped off, i think its R134. otherwise it would be a good idea to switch to this.

ffpmlex · 08-24-2005, 02:42 AM

The A/C compressor disengaging keeps the temperature normal!

asm · 08-24-2005, 03:00 AM

Possible freeze at the expansion valve.

Freeze is usually cause by the moisture in the system. Of course, like someone else mentioned, it could just be the expansion valve is bad...

ASM

SnakeyeS · 08-24-2005, 06:05 AM

Make sure your air switch is on "reciruculation" and not "outside air". This helps tremendously. Some american cars make this switch automatically when u turn on the air but not my camry.

freestylez · 08-24-2005, 06:31 AM

Quote:

Originally Posted by SnakeyeS

Make sure your air switch is on "reciruculation" and not "outside air". This helps tremendously. Some american cars make this switch automatically when u turn on the air but not my camry.

yea if u turn on both buttons AC / Recirculation at the same time the AC will be cooooold, if i dont turn on the recirculation button my AC is warm as hell

CDub LXi · 08-24-2005, 07:41 AM

I never put my A/C on recirculation... any smells in the car (food, cig smoke, etc) will stay in the car and over the course of years and years it'll stay in so you can smell it when you turn your A/C system on. The past 4 cars I've owned I didn't use the recirc function and never had a problem with proper cooling.

ruoknow · 08-24-2005, 09:25 AM

Quote:

Originally Posted by freestylez

yea if u turn on both buttons AC / Recirculation at the same time the AC will be cooooold, if i dont turn on the recirculation button my AC is warm as hell

thanks guys/gilrs. yes, i alway turn on the "recirculation" when i am using AC to get a more effeicient result. It still behaves like that. I think the problem may be associated with some switch or valve.

No body has the some problem as what i have?

freestylez · 08-24-2005, 10:33 AM

get a couple of cans of refrigerant might solve the problem then

AdamS · 08-24-2005, 11:19 AM

(As mentioned previously) Your evaporator could be freezing up, on account of the faulty expansion valve. When it freezes up it does not allow air to flow through and be cooled. Do you notice a difference in airflow at all? Course it may not prevent airflow, but at times it does.

You really need someone to go over the system. Besides, the repair will require equipment that you more than likely do not have in your garage. You could just get someone to evacuate the system and then you could replace the part.

There is the potential that you have an insufficient amount of freon in the system. Have that checked, and you probably need a manifold gauge set to ge hooked up to properly diagnose the problem...

-Adam

ruoknow · 08-24-2005, 11:32 AM

Quote:

Originally Posted by AdamS

(As mentioned previously) Your evaporator could be freezing up, on account of the faulty expansion valve. When it freezes up it does not allow air to flow through and be cooled. Do you notice a difference in airflow at all? Course it may not prevent airflow, but at times it does.

You really need someone to go over the system. Besides, the repair will require equipment that you more than likely do not have in your garage. You could just get someone to evacuate the system and then you could replace the part.

There is the potential that you have an insufficient amount of freon in the system. Have that checked, and you probably need a manifold gauge set to ge hooked up to properly diagnose the problem...

-Adam

The airflow keeps the same, while the only difference is temperature.

I am thinking if the evaporator is freezed up, that should be cold enough (cuz it's frozen, even without the circulation of R134a) to get a good ac.

The above conclusion could be wrong if a normally circulated AC system gives a temperature (at evaporator) way lower than a freezed one.

AdamS · 08-24-2005, 11:41 AM

^hmm, don't really know what you are saying...but it takes time for the evaporator to freeze over, and actually 30 minutes sounds about right. Usually the system will work perfectly, and then after a period of time it stops cooling altogether. If just the expansion valve is freezing up, then your freon will not pass through the evaporator and remove heat from the passing air.