I'm having a strange problem with the air conditioning system in my 1998 Tacoma. It is a regular cab with the 2.4L 4 cylinder and automatic transmission.

Quick history on this issue. Up until a month or so ago, the system was completely original. It wasn't getting very cold any more so I had my AC guy come and take a look. He diagnosed a leaking evaporator core. He replaced it, evacuated system and recharged it. It seemed to work fine for a couple of weeks but then stopped getting cold after driving for 30-40 minutes. I took a look under the hood to see if the compressor was engaged and found the AC line to be frozen (looked like a white popsicle).

My AC guy suspected a bad thermistor which we then replaced. He didn't have a thermistor with the correct connector on hand so he cut and spliced the original connector with the new thermistor. This didn't solve the problem.

He felt the only other thing that could cause this would be a bad AC amplifier. I managed to find an allegedly new OEM amplifier on Ebay for a good price and installed it. It did look new and matched the OEM one exactly. It initially seemed to be working well as the system cycled pretty quickly while running in my driveway. I thought all was well as it didn't freeze up after a 20 minute drive to work this morning. The drive home took a bit longer however and I found the AC line frozen once again.

My next course of action is to try the correct OEM thermistor. I picked one up from the local dealer (only $6) but I'm not too optimistic. The AC guy said he has never had this happen before and is out of ideas. I do trust him as he has been in the auto AC repair business for 25+ years and has always done good work for me. He probably wishes I would just go away at this point.

Any AC experts out there with some ideas or known Tacoma AC issues I am unaware of?

Thanks for any input!

 

Find someone who knows what they are doing!!

Then we all get those problem trucks once in a while

All thermisters are not equal does the non stock one that was replaced operate on the same scale ??

Pretty hard to trouble shoot when you don`t mention any pressures .

First thing any one is going to do is hang the manifold gauges on you need a place to start.

Real High humidity will cause the line to freeze no insulation on yours??

The Evap coil freezes to the point you no longer get cold air ??

 

Not sure what the pressures were but the AC guy said the system was full.

Have no idea on the compatibility of the thermistor. I am going to try and put in the new OEM one after work today.

I am in Honolulu, HI so it is always pretty humid here but it has never been an issue before.

Yes, it freezes to the point that the air isnt cold any longer.

The insulation is still on the line.

​​​​​​​Thanks for your reply I appreciate it!

 

If your sure the system is charged correct .

Unless your Toyota Thermister cures the issue the compressor is not cycling like it should .

Condenser good and clean??

Well below freezing here I can`t get into AC trouble shooting it just feels so wrong

 

Replaced the thermistor this afternoon. It did cycle several times in 3 or 4 minutes while running in the driveway so I am hopeful.

We'll see how it goes tomorrow on the commute to work. Anybody know if it is possible to access the evaporator core by removing just the lower half of the enclosure?

I pried the two halves apart to replace the thermistor but managed to bust the plastic clip that holds it in the core as well as a bunch of the fins on the evaporator. Going to pick up a new clip and replace it tomorrow but would like to get better access to avoid any further damage.

 

rdsrf,

did the new thermistor solve the problem? I'm also having problems with a freezing evaporator and non-cycling of the compressor.
Thanks!

 

rdsrf,
That was a common occurrence with the older Jeep TJ's. My 99TJ did it on a couple of the really hot days(back around 2000). A very hot and very humid day would produce cold air for awhile but it would get warm like you say....it was the evaporator under the dash freezing up. No fix for it that I was aware of. My 01 tacoma does not seem to do that though thank God.



https://www.google.com/search?q=AC+Evaporator+Freezing+Up&rlz=1C1CHFX_enU S736US736&oq=AC+Evaporator+Freezing+Up&aqs=chrome. .69i57j69i60l2j69i61&sourceid=chrome&ie=UTF-8

So much cool info of freeze-ups out there.....wonder if your evap is dirty?

 

It's hard to pinpoint ac components that are the culprit. Pressures tell a little, but not the whole story, though it's definitely what I would want to know too. But something for sure is holding up the refrigerant. You may need to take stuff out just to look at the evaporator, condenser, etc. They are a pain to access, but then again, isn't most stuff we deal with?

Bet the moisture got into the whole system and did its dirty work. I have an issue of no a/c on my Accord. So I'd be curious to know what you find caused your problem. Just a thought, but is your compressor fully functioning? Maybe it's on its way out. Maybe check if electrical connections are intact. It's easier to check, compared to other components. Otherwise, could be a restriction in the other lines/components. Since parts are being replaced blindly, I'd start over and fully check. Wish I had something more definitive.

Let us know.

 

Condenser freezing is usually caused by restricted air flow through the evap core or bad expansion valve/block. Can also be caused by low freon or bad thermostat. This is generic info. Not sure how your circuit works. Never had to work on any of my third gen Runners. Some pressure readings would be helpful for further diagnosis.