Toyota Nation Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
46 Posts
Discussion Starter #1 (Edited)
Hello everyone, I have a problem. The a/c in my car is blowing hot air all the time no matter the speed of the blower. The system is fully charged, the compressor is coming on briefly and some lines are cold to the touch while others are warm. I first noticed the problem in the dead of winter because the heat in my car is unbearable whenever I use the defroster. The car has climate control and I still get a little heat if I turn to knob to sixty five degrees. I read online that it is the expansion valve that is bad. I dont want to go and change the valve and it is not the valve, that is why I am putting it to you guys. I do not even know where the expansion valve is located. Does anyone know where it is located incase I have to change it? I am standing by to order my manifold set online to do the repairs myself. I know I have to recover the refridgerant gas from the system, a shop will do that for me. Thanks in advance guy. The colling fans do come on when the a/c button is pressed. 1998 Avalon 245,000 miles.
 

·
Super Moderator
Joined
·
12,595 Posts
The expansion valve is attached to the evaporator, which is up under the dash. I think a bit on the passenger side of middle.

It would be best to have high and low pressure measurements before concluding it’s the expansion valve. It could be overfilled. Or it could be the compressor is bad.
 

·
Registered
Joined
·
46 Posts
Discussion Starter #3
BMR, thanks for your input. I did some checking and testing on the system today, I have good news and bad news. I hooked up a manifold guage set to the system and this is what happened. I turned on the a/c on high and it got cold throughout the diferent settings. The low guage was reading not more than 30 PSI and the high side was giving me around 110/120 PSI. Outside temperature was around 52 degrees with the compressor cycling on and off and the fans all working. The sight glass was clouding up everytime the compressor comes on. I Turned it off and it took about 20 minutes for the two guages to give the same reading. I tried it again in the presents of my brother and he said that the a/c is very cold with the two front windows down and doors opened. I left the yard a few minutes after that with the a/c on and it stopped working about a minute later. I started getting hot air although the temperature control knob was on 65 degrees and the a/c light was still on. I forget to rev the engine up to 1500 rpm to see what happens, I will have to do the test again. I have automatic climate control in my car. I personally don't think it is the expansion valve. Why would I get hot air coming up when the temperature switch is set to 65 degrees? The a/c system was never opened since I got the car in 2005 and it was working fine all the time. I don't think it was ever opened by the first owner, I am the second owner. Thanks for any help guys.
 

·
Official PITA
Joined
·
496 Posts
Tis won't exactly be helpful, but... I had an '05 Avalon, and using the A/C, during summer, at various times it would decide, on its own, to put out HOT air to the rear vents. If you shut the A/C off for a few minutes, the problem would go away, and not come back for several hours.



It was diagnosed as some sort of air-mixture ?blend-valve? -part of the automatic A/C temp system- hidden way under the dash. Large price tag to fix, so I just lived with it.
sounds as if your problem may have a similar source.
 

·
Super Moderator
Joined
·
12,595 Posts
Based on what you just said, I think it’s simply low on Freon. But get the pressures checked with it idling at 1500 RPM. That’ll drop the low pressure side a fair bit. Can you override the automatic system? You need to have the fans on high, the temperature control on max cooling, and the idle at 1500 RPM. And it would be best if the outdoor temp was warmer, like above 70°F.

Here’s a good troubleshooting guide from Denso.
 

·
Registered
Joined
·
46 Posts
Discussion Starter #6
Guys, I just came home from work and doing some trouble shooting at my work place parking lot. Some weird things happened while I was trouble shooting the problem.I am getting slightly cold air when I turned the temperature selector to high and I am getting hot air when I turned it to sixty five. The key to solving the problem is, why am I getting hot air when the temperature selector is on sixty five degrees and the compressor is cycling on an and off? I think a valve behind the dashboard is not doing what it is supposed to do. What goes on behind the dashboard when heat or a/c is selected? what prevents the two of them from coming at the same time? Riick, I think I have the same problem you had on your 05 Avalon, I am not going to live with mine. BMR, I did idle the engine at 1500-2000 RPM earlier today and the reading was, 27 low and 205 high. I started to get cold air at one point and as soon as I gave it gas to go up to 1500 RPM, it started to give hot air and the compressor was on. By the way, I opened the automatic climate control module to see if anything was wrong with it, everything seems ok. I put it on automatic on my way home and was playing with the temperature selector to see if I will get cold air.The blower motor was going from low to high everytime I turned the temperature selector from extreme left to extreme right. That tells me that the temperature selector is working. I have to get this fixed before the summer and I am not going to shell out no big bucks to do it. One more thing, the pressure between the low and the high equalize in about 15 miutes.
 

·
Super Moderator
Joined
·
12,595 Posts
Sounds like the AC system’s charge is good, and the compressor is putting out a decent high pressure. I think everything is good there.

Some vehicles have a blending system in the duct work. Warm air is mixed with cold to provide air to the cabin that is the right temperature. I’m thinking that control system is on the fritz. I have no experience working on those, so I can’t offer any further advice, except to say if you can’t figure it out, you might take it to an independent shop that specializes in automotive HVAC systems. If they have to tear into the dash to replace a faulty servo motor on a damper door, it might get expensive. But I’m speculating quite a bit there.
 

·
Official PITA
Joined
·
496 Posts
It was easy for me to live with problem, it was only intermittent. Yours is constant.
You'll figure it out, .... maybe bypass the automation, if possible
 

·
Registered
Joined
·
46 Posts
Discussion Starter #9
Hello everybody, I found an old post with someone who had the same problem that I am having at the moment. The blend door actuator was acting up in his case. It is the door that opens to give you heat or a/c when either one is desired. The actuator is a real pain to get to, according to the post. I am going to look at mine when I go leave from 31 st of May and will update you guys.
 

·
Registered
Joined
·
46 Posts
Discussion Starter #10
Hello guys, I think I found the source of my A/C problems. Even if I change the blend door actuator, the a/c will not work. Why? Because the heater valve in the engine bay is stuck in the open position and the actuator motor is not powerful enough to move the arm that is attached to the cable. That valve is really stuck, it is supposed to be moved by your finger, my finger will break. Not even Hercules can move that thing. I watched a few videos of people moving that valve with their finger and it was moving freely. I was trying to remove the blend door actuator but could not get it out, even after I removed the four nuts from the vertical metal bar. The bar was shaking a little but I still could not remove the bar so as to get out the final screw that is holding the actuator in place. I decided to get creative and drill a hole in the the metal bar directly in front of the screw, I did not drill the hole because I could not find the key to open the drill chuck. I am going to change that valve ($35 ) first and see what happens. Even if the acutator is bad, I suspected that it is the valve that caused it to go bad because the motor is not powerful enough to move the stuck arm on the valve and it either burn out thr motor or damage the gears. One more thing, I did unplug the harness from the actuator and was still getting heat instead of a/c, that is what caused me to check the heater valve in the engine bay.
 

·
Registered
Joined
·
46 Posts
Discussion Starter #12
Hello everybody, my a/c now works. I was able to remove the cable from the arm of the heater valve and manually turned off the valve. It was not the valve that was stuck, it is the cable that is stuck. No more heat coming through the vents when I am driving.
 

·
Registered
Joined
·
728 Posts
Nice fix. There is such a thing as a cable oiler or cable luber. Assuming you can get the business end out of the retainer, you might be able to resurrect your existing cable. They're marketed to bikers / snowmobilers, but as long as you have a conventional actuating cable, with a stationary outer wrap and an moving inner cable, a luber should work.

EDIT:
Just found this YouTube video that shows 2 methods -- ghetto oiler from plastic bag, and commercial cable oiler. The removal bits don't apply, but the methods begin around 0:53: https://www.youtube.com/watch?time_continue=152&v=aQnMdOL09uY
 

·
Registered
Joined
·
11 Posts
Hello everybody, my a/c now works. I was able to remove the cable from the arm of the heater valve and manually turned off the valve. It was not the valve that was stuck, it is the cable that is stuck. No more heat coming through the vents when I am driving.


A picture would be helpful.:wink:
 

·
Super Moderator
Joined
·
12,595 Posts
Here's a drawing of it. It's mounted on the firewall in the engine bay.



Here's a video; not an Avalon, but similar.
 

·
Registered
Joined
·
11 Posts
Well, I sent my son in florida,I am in NY,the aforementioned ac amplifier the mechanic told him needed to be replaced, and no joy. His ac is sometimes working,sometimes not.Freon level is good.Any ideas?Thanks
 
1 - 16 of 16 Posts
About this Discussion
15 Replies
5 Participants
chich
Toyota Nation Forum
ToyotaNation Forum is a community dedicated to all Toyota models. Come discuss the Camry, Tacoma, Highlander, 4Runner, Rav4 and more!
Full Forum Listing
Top