Weak Gen2 Air Conditioner mystery puzzle; dealer can't fix

Folks, I'm resurrecting this rather old thread because I just experienced something similar with my Gen II (2007). A couple of weeks ago, I drove down to Savannah, and the temperature rose to 81 on the drive down, unusually warm for December. The A/C came on, cooled the car for about half an hour, and then started blowing warm air. Turning the climate unit off for about ten minutes and turning it back on got the air blowing a bit cooler, but only for about ten minutes or so.

I bought this car with 97K on it, back in November 2012. A/C worked fine then, at least for drying out the car when it rained. When weather got warm, it was blowing warm air, so I took it to the dealer and they recharged the system in March 2013. They injected a dye to trace any leaks, and they checked it a month later and again when I took it in yesterday. No leaks. They checked the A/C out and they found no issues, because back in NJ, it's 35 degrees and the A/C works fine when it isn't that warm outside. I noticed this too, on the drive back up two weeks ago -- when the temp dropped to 65 outside, the A/C was ice cold.

Checking through the repair records online, I saw that the previous owner had the A/C recharged in May 2012. So it looks like this has been an issue for a while. If there's enough freon and the system works fine when it isn't so hot outside, what gives? The Toyota tech said there were no codes in the OBD, so as far as the Prius was concerned, all was well.

But all was not well. The car was hot and unpleasant. My guess is that something is overheating, but I don't know what, and nobody else seems to, either. Any ideas? BTW, I don't think this was a psychological thing, but when the A/C got weaker, it felt like the fan was also running slower. Again, the tech said there was nothing wrong with the climate system at all.

One more thing -- I'm still on the original 12V. That should have no bearing on this, right?

- Sung

 

The 12V will have no bearing on this.

Multiple recharges with 1 year is NOT a good sign. It could be overcharged or it could have too much moisture. Hope for the former. You need to take it to an expert in A/C repair, probably not a dealer. The first step would be to do a deep vacuum pump-down of the system for at least half an hour to boil off any moisture and then do a refrigerant charge to the specified amount. Wait until you are in a warm enough place that you can't bear it anymore. It is much easier to diagnose and repair A/C in hot weather.

 

Somebody who actually knows that the air conditioning compressor oil used in Toyota hybrids (other than Classic) is a special type which does not conduct electricity (ND 12) and that air conditioning equipment used to service regular vehicles cannot be used with the Toyota hybrid AC system.

 

I don't know if the car system is the same as a ac system in the house. I had a new ac installed and it would have the same problems you mentioned. The system I had was somehow overfilled and the compressor would turn on for a few minutes and stop. The techs came by to adjust the freon, kept adding and reducing and still did not work properly. It just wouldn't stay on.

Finally a supervisor came out and drained the entire system out, started from scratch. Filled the system to the proper amount and then it was all fixed. The system didn't operate properly due to it having the wrong amount of freon, either too little or too much. Just thought I shared it was quite similar to your story.

 

Thanks, guys, for your advice -- I'll seek out an expert in my area. Hopefully there's somebody within reasonable driving distance who can help.

One thing I don't understand -- why was the problem fixed when I took it in back in March 2013? The A/C was inoperative (warm air all the time), then they recharged the system and it worked fine throughout all of the summer, when the temp went well into the 90s.

FYI, here's the exact snippet from what the dealer entered into the system for the repair:

EVACUATED & RECHARGED A/C SYSTEM WITH REFRIGERANT AND DYE. ADVISED CUSTOMER T ~|~CUSTOMER STATES AIR CONDITIONER DOESN'T GET COLD. ~|~LOW ON REFRIGERANT, NO LEAKS DETECTABLE AT THIS TIME ~|~EVACUATED & RECHARGED A/C SYSTEM WITH REFRIGERANT AND DYE. ADVISED CUSTOMER TO RETURN FOR INSPECTION TO FIND LEAK.

Since they said it was low on freon, it makes me believe that the problem I'm suffering from now is a different issue, either of too much freon or moisture. What do you think?

 

I think you should fill out your profile so we can see where you live.

In the meantime are the ac assist fans working properly and installed in correct flow? Both on when ac on? Both sucking in air into engine compartment? Is the car missing the bottom engine plastic engine cover and exposing the condenser to fod? Is the front of the condenser bug logged?

 

Ed -- just did so -- sorry about that. I didn't realize my location wasn't showing up. I'm in NJ, ZIP 07882.

I haven't done much examining myself of the A/C unit, though I have seen the flow of the freon through the sight glass. One think you mention has gotten me curious. In April last year, I hit a swath of tread on the highway and it took out my front bumper and some other shields underneath. I had it all replaced, but "the bottom engine plastic engine cover and exposing the condenser to fod" -- I wonder if something like this is happening. How can I tell if the bottom engine plastic cover is on? I spent about $400 for the repair, because I specifically did want to protect the parts from debris.

 

Alot of posters with leaks here end up being fod damage to the ac condenser which as you know sits in front of the radiator and will take the brunt of road debris damage. This exposure is exacerbated by the absence of the bottom engine cover which protects the condenser from fod kicking up and hitting it the somewhat fragile aluminum condenser or at the very least damaging the fin structure reducing cooling. The condenser will not last long without the cover especially if you live in a somewhat rural area.

Take off the black plastic TOP engine cover the one that covers the rad. Snake hand around underneath the cover screws. Using the snaked hand behind push out the screw while turning it lefty loosey with a Phillips. Those 6 screws should pop right out.

This gives you good view of the face of the condenser. Look down. if you see the ground your missing the engine cover. if you can't see the ground and you see the plastic plate your ok.

Take a good look for any bent fins or obvious damage or leaking refrigerant. To naked eye might present itself as a dirty grease smear. Need UV googles to see leaking refrigerant dye.

It may require a good cleaning. Home D sells a pressurized spray can of ac coil cleaner with a blue cap. Rinse condenser off with garden hose. Soak condenser with that cleaner. Let sit. Scrub gently any really clogged area's but do not damge the fins. Home D also sells a fin comb used to straighten fins. Be gentle!!!

Rinse. This cleaning alone usually will improve cooling efficiency greatly. It is a required maintenance item once a year at lest so clogged bugs do not become corroded. Condenser replacement is very expensive and deserves some attention.

Just like your house inside & out.

 

One thing to check if the car has had front end repairs or the condenser replaced is the direction of air flow from the two electric fans that blow air through the condenser and radiator.
These fans counter rotate, and if fitted in the wrong positions will cause this problem. To check for this stand close to the front of the car with the AC on full. If you can feel air blowing out of the front grill the fans have been changed over. The air flow should be from the front of the car into the engine compartment.
The fix is to change the position of the two fans "not the motors", taking the fans off the motors and interchange them.

John (Brtprius)

 

See post #26

 

Sorry missed that.

John (Britprius)

 

Hey folks,

Just wanted to update this thread to let you know what happened with my 2007 Prius. The dealer found the leak -- the AC low side pressure line. Expensive job -- $650 for the replacement of the line. AC is working fine now, but I won't be convinced until next year, when hopefully it will keep working fine.