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Ask Chad Farhat Your Own Question
Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: Toyota
Satisfied Customers: 3975
Experience:  Owner at Carolina Auto Service & Sales , 20 years Experience in Foreign & Domestic vehicles
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98 RAV4. A/C works sometimes, but blows very hot at other

Customer Question

98 RAV4. A/C works sometimes, but blows very hot at other times. (It's not contingent on the weather. I've had it crap out on me in 70 degree weather.) AC button on, green light works. System charged, but not overcharged. A/C system has been vacated and refilled. My mechanic (not an A/C specialist) couldn't figure out the problem. And tearing out the a/c is a big job, I'm told, due to its location. (Since I'm still driving a '98, it should be clear to you that I don't have a lot of money to throw at this, but I live in the intolerably hot valley of LA, so I'd be very grateful if we could figure this out.)I've found conversations in forums that say a clogged expansion valve could do this. Would that make sense? And if so, is it true that it can be easily accessed by going through the glove compartment?
Submitted: 2 months ago.
Category: Toyota
Expert:  Chad Farhat replied 2 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Customer: replied 2 months ago.
Sometimes the AC will work for a while, then start to blow hot air.
Expert:  Chad Farhat replied 2 months ago.

Hey how are you

the clogged expansion valve could be an issue if the ac compressor locked up and contaminated the system but then it will not cool at all

are the fans are running at time the ac not cooling ?

does the mechanic has ac gauges to tell us what are the low and high side pressures ?

to know if you have restriction in the system on the expansion valve issue ,then when ac running looking at the high side gauges you will see the pressure rises pass the 150 psi mark and when it reaches 250 psi the high pressuer switch cut the compressor off until the pressure settles and will keep on doing that back and forth ?

if you get me those readings i can tell you more

a good ac system readings should be low side 25 to 45 psi and high side 150 to 175 psi when running ,

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Customer: replied 2 months ago.
are the fans are running at time the ac not cooling ?
Yes, it will blow hot like a hair dryer.does the mechanic has ac gauges to tell us what are the low and high side pressures ?
I saw the mechanic when the problem started, last summer. If I recall, he said the pressures were fine, but I don't remember what they were. Is this the sort of data that I can get for you by measuring it myself with a tool from the auto parts store?
Expert:  Chad Farhat replied 2 months ago.

yes ,if you can get me the low side & high side readings on the ac pressure lines i can tell you what is wrong and be more accurate

A good working ac system should read 25 to 45 psi on low side

and 150 to 175 psi high side when running ?

this can be done by using ac gauges tester hooked up to the ac line connection ports

if the ac system has low freeon ,it will cut ac compressor off and you will feel just warm air ?

if the high or low side switches malfunction will cut ac compressor off

lets start with there pressures and we go from there

when u get them just post them back here for me and i can help you further

if the low side pressure shows above 45 psi, it will tell you the freeon levels are low

if the high side shows pass 175 psi ,u have a restriction the in the system and like a clogged ac condenser or expansion valve etc..

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Chad Farhat
ASE Certified Technician

Please let me know

Thank You

Chad Farhat

ASE Certified Technician