96 Camry A/C Problem...HELP!

[mytoy]

My 96 Camry A/C cools normally for about 20 minutes, then begins to
lose its cooling effectiveness. When cooling ability diminishes I can also
sense a change in humidity, like when it rains.

Here's whats been replaced chasing this:

- New Denso Compressor(not a rebulit one)
-Evaporator
-Condensor
-Expansion Valve
-Filter/Dryer
-Pulled a vacuum on system and recharged

After all these repairs, issue remains. I then took to Toyota dealer and
had them try. They felt the Expansion Valve I already replaced was defective.
They replaced the valve and still not solved. Afterwards they said they found a
clog in the high pressure line and the Dryer which I had already replaced. They
replaced the Dryer and cleared the clogs(so they say). They gave me the car back
yesterday, used the car today and nothings changed. Cooling ability still diminishes
after 20 minutes or so. This car always had amazing A/C before this nightmare began.

I've dumped over $1300 on this....! If this wasn't such a great runniing car I would have
dumped it. I feel trapped, does anyone have a clue as to what could be wrong?

....Desperate.

[johnjan]

I am a novice at this, but did you charge full with refrigerant?

[mytoy]

Originally Posted by johnjan

I am a novice at this, but did you charge full with refrigerant?

Of course. Multiple times by multiple shops including Toyota as I already explained.

[Stillrunning]

Increased humidity is just less cooling at evaporator. Can you verify that compressor clutch is engaged when you loose cooling? Why was compressor replaced, that seems an expensive "try"? Did new compressor include new clutch? Have you taken Hi/Lo pressures when system cooling reduces? Stupid question but have you checked belt tension when system reduces cooling?

[mytoy]

Originally Posted by Stillrunning

Increased humidity is just less cooling at evaporator. Can you verify that compressor clutch is engaged when you loose cooling? Why was compressor replaced, that seems an expensive "try"? Did new compressor include new clutch? Have you taken Hi/Lo pressures when system cooling reduces? Stupid question but have you checked belt tension when system reduces cooling?

Yes, I understand the humidity change feeling is due to
cooling being compromised. Yes, the new compressor came with
new a clutch. Belts are relatively new, this car is always well maintained.
The compressor ws changed becuse the car has 175K miles and original
mechanic working on the problem said he felt it was making noise and
pressures were varying so he said must be changed. Thats where this
journy of parts replacing began. He gave up, said he could'nt solve this after changing all the stuff I listed in originl post. Then I gave it to Toyota and they haven't solved anything after their work which I explained in my post. No, I haven't personally looked at the pressures when the cooling stops. I do notice now that both pipes coming off the compressor are hot. One very hot, other just reltievly hot which used to be cold and covered with condensation, not now.

[Stillrunning]

Here's the first thing I'd do, unless it's already been done. Take the water valve out of the heating loop. If the water valve is leaking or defective then it will just heat the cooled air from the evaporator, that may explain the hot(er) outlet pipe from the evaporator, varying pressures and why this only happens after 20 minutes when the engine is at full temp. I'd disconnect the valve and plug the hose once that is done see if your problem goes away. If not then we need to look further into the A/C system.

[91boz]

Try posting your problem here .. http://www.autoacforum.com/

[mytoy]

Originally Posted by Stillrunning

Here's the first thing I'd do, unless it's already been done. Take the water valve out of the heating loop. If the water valve is leaking or defective then it will just heat the cooled air from the evaporator, that may explain the hot(er) outlet pipe from the evaporator, varying pressures and why this only happens after 20 minutes when the engine is at full temp. I'd disconnect the valve and plug the hose once that is done see if your problem goes away. If not then we need to look further into the A/C system.

I actually suggested this to the initial machanic shop who I started with chsing this problem. He dismissed as not the cause. I just assumed he and now Toyota would have sniffed at this possibility. I'm going on belief this has been eliminated as contributing cause.

I tryuly appreciate the advice...


Bob...

[mytoy]

Originally Posted by 91boz

Try posting your problem here .. http://www.autoacforum.com/

Thanks for the suggestion...I will do so.

[69GTSport]

Air keeps blowing thru the vents at the same speed and it just gets warmer and then no cooling? If so, make sure the compressor is actually engaged, may be a relay, pressure switch, or circuit problem if it's not. Also, see if the condenser becomes super hot to the touch (be careful!). If so, there may be a radiator airflow restriction problem (dirt clogging outside of radiator's cooling fins and not allowing airflow to pass thru it, thus restricting the fan's ability to pull air thru the condensor which is in front of the radiator) or electric fan issue (not turning fast enough).

[mytoy]

Originally Posted by 69GTSport

Air keeps blowing thru the vents at the same speed and it just gets warmer and then no cooling? If so, make sure the compressor is actually engaged, may be a relay, pressure switch, or circuit problem if it's not. Also, see if the condenser becomes super hot to the touch (be careful!). If so, there may be a radiator airflow restriction problem (dirt clogging outside of radiator's cooling fins and not allowing airflow to pass thru it, thus restricting the fan's ability to pull air thru the condensor which is in front of the radiator) or electric fan issue (not turning fast enough).

I'm sure your suggestions are well meaning but do understand this problem has been wrestled with by highly qualified mechanics including my Toyota dealer service department. Just so we're clear...car has new radiator, as well as all the A/C components I listed in initial post. So no...there's no air restrictions. Also, the compressor is NOT cutting out and the fans are working. Needless to say these are all items already well investigated.
On Wednesday its going back to Toyota.

[Stillrunning]

When cooling reduces/stops do you still get the same amount of air blowing through the vents? If evaporator is freezing up due to faulty thermo sensor then ice/frost can block evapoator and you will get little to no cooling.

I also don't know why you came to this site for help. Every time someone attempts to help, you dismiss it saying "experts" have already looked at that. You also don't seem to have the equipment or desire to tackle some hands-on investigation yourself and would rather throw money at this. What magic solution (given you've replaced the entire system) are you looking for here that anyone can pull out of the air?

[mytoy]

Originally Posted by Stillrunning

When cooling reduces/stops do you still get the same amount of air blowing through the vents? If evaporator is freezing up due to faulty thermo sensor then ice/frost can block evapoator and you will get little to no cooling.

I also don't know why you came to this site for help. Every time someone attempts to help, you dismiss it saying "experts" have already looked at that. You also don't seem to have the equipment or desire to tackle some hands-on investigation yourself and would rather throw money at this. What magic solution (given you've replaced the entire system) are you looking for here that anyone can pull out of the air?

Answer to your question: There is no loss of air flow, neither in the car
through the vents even when cooling diminishes, nor through the radiator and condensor. As stated, all are new.

Sir, if you think you're frustated by this how do you think I feel after trying to get this solved and paying nearly $1500 so far. I post the facts of this problem with no embelishments(nor emotion) hoping some of the experts who peruse the forum might have experineced this and can advise.

Only new thing I observe since I picked up the car at Toyota last week is the tube coming off the Compressor that usually is cold and sweaty is actually quite warm. Not hot like the other one but it is warm and no condenation on it. This is a change since they replaced the second Expanasion valve. Don't know if this is meaningful info.

Thanks for your interest...