2/93 A/C Mystery - Need Ideas and Help

[-Spike-]

LOL, glad you found them. I get (unreasonably) frustrated when people don't read through old posts to solve their current problems, thinking they are the first to have that particular malady. Almost everything I have problems with on my vehicles has been fixed with help from the archives.

Can't go wrong with Toyota parts, I have yet to find any aftermarket parts that were better than OEM. As a side note, are you aware you can 'rebuild' your old Toyota fan clutch? The dealer (and therefore CDan, I'm sure) sells the silicone that 'powers' the clutch. Replace it and you're almost good-as-new. Almost, because unfortunately they don't offer the seal that holds the silicone in. Also, apparently there's some debate on whether the spring which activates the clutch fatigues. I haven't tried to rebuild mine yet so I don't know if there's a way to remedy a leaking seal or a fatigued spring. I did buy the silicone, which comes in 2 small tubes and IIRC they cost around $15. After I bought it, I tested the fan clutches (per some old post here) and they are fine, so I'm saving the silicone for experimenting at a later date.

-Spike

 

[FJ809496TLC]

Your high side pressure is too high. Assuming you vacuumed the system properly, put the right amount of freon, check the air mix servo motor/cable and a/c control cable(water valve control cable) to make sure you are not mixing cold/hot air.

 

[Gieser]

Your high side pressure is too high. Assuming you vacuumed the system properly, put the right amount of freon, check the air mix servo motor/cable and a/c control cable(water valve control cable) to make sure you are not mixing cold/hot air.

We did all of this. We still get a high reading. We have flushed the sytem 3 times, no blockage.

Is it possible that the reading would be high if there was not enough air passing through the condenser?

 

[Bear80]

If the high side is still reading over the range, then it's too hot outside. You really need to run that water hose on the condenser and watch what happens.

A/C systems are not complex by any means. If you still unknowingly have a blockage, then it will most likely be backed up now at the expansion valve and mear flushes will not get it out.

 

[-Spike-]

A blockage will show as a vacuum on the low side. High outside temps will show as high pressures, as will too little air across the condenser.

-Spike

 

[Gieser]

If you still unknowingly have a blockage, then it will most likely be backed up now at the expansion valve and mear flushes will not get it out.

We changed the expansion valve (for the third time) yesterday just to make sure.

 

[Gieser]

from Spike: A blockage will show as a vacuum on the low side. High outside temps will show as high pressures, as will too little air across the condenser.

Thank you, I was not aware of this.

We are putting on the Toyota Fan clutch today. Once that is completed, I will get with Tom (the A/C man) and run a hose over he condenser while running in the hot air. I am anxious to see what happens.

 

[IdahoDoug]

My money's on something being left in the system that's now in the condensor blocking it just like when you first had it worked on. For it to work properly says everything was working fine. For it to stop working properly but nothing changed except freon flowed around for a day or so, points right at the blockage again.

DougM

 

[FJ809496TLC]

Yes. If you don't have enough airflow through your condenser, the pressure will be higher. Based on your pressure readings, partial restriction still exist. Recheck line from the condenser outlet, receiver/drier and all the way down to the EXV. After finding the restriction, recheck your refrigerant charge and check your sightglass.

 

[Gieser]

UPDATE ON SITUATION:

Low is reading about 30 and High is reading about 220. So everything looks good. I drove around and on the expressway I was happy with it pretty consistant (in the vent) at about 55-56 degrees. On city driving, about 57-60 degrees. When sitting idle, it will go to about 62 degrees. So it seemed to be working . That being said, after I parked it for about an hour, I got in and started it up and it would not go below 70 degrees (even after I ran it to get the hot air out), and the readings were the fine on the guages (same as stated above). I hit the A/C button to turn it off, then back on and it got colder. I heard something I never heard before (maybe I just missed it), but the was a click coming from the area where the evaporator is behind the dash. It would click, and the system got cooler, then click again and it would back off. No seeming timing to it, and the compressor was enguaged the whole time.

I have not tried to run water over the condener, yet, but will tonight. Maybe the system isn't really charged all the way??? Any of you have any ideas?

 

[medtro]

AC amplifier is located is the area you described.

 

[-Spike-]

The what is located in that area???

The clicking you describe might be the temp sensor shutting off the compressor because the evaporator core is too cold. I don't know for sure if there's a relay in that area, but I'm sure you saw the temp probe when you opened the evap core box to replace the expansion valve. Unless, as I gather from earlier posts, you didn't do the work yourself, in which case you'll have to take my word for it.

Back to medtro, what the heck is an AC amplifier?

-Spike

 

[Rich]

...what the heck is an AC amplifier?...

Big bucks electronics in small package.

 

[medtro]

"Whenever the air conditioner is running, a small computer called an air conditioning amplifier constantly monitors compressor rpm and compares it to engine speed. The air conditioning amplifier, which is made of a black plastic material and is a little larger than a pack of cigarettes, is usually located on or near the evaporator case."


Copy from here . There is more info there.

 

[-Spike-]

OK, that's very cool. More kudos to Toyota, as opposed to LC specifically, for putting in a sensor that determines if the compressor is spinning at the correct RPM, and shutting the system down if the compressor isn't running correctly. I guess that might be your answer as to why your A/C keeps getting warm.

-Spike

 

[RavenTai]

the AC amp should be solid state and therfore would not make noise,

there are three realys in that area, all three have to do with turning the compressor on and off for various reasons. are you sure the compressor is not stopping?

there are also several servo motors that control air control dampers, the hot/cold damper could also keep the AC ouput from beign as could as it should

 

[-Spike-]

The A/C amp might be cycling one of those relays you mentioned. Belt tight?

-Spike

 

[RavenTai]

yep

 

[Gieser]

Unless, as I gather from earlier posts, you didn't do the work yourself, in which case you'll have to take my word for it.

I checked that sensor and it was okay.

I made a mistake about the clicking. The click I am hearing is the in the area of the evaporator and expansion valve, and it IS switching the compressor on and off. There does not seem to be any certain time or pattern. It won't relly get bolew 54 degrees (even first thing this morning), but will fluctuate up to 68-70 degrees. Seems to be staying around 60, which just isnt cold enough in 100 degree 80% humidity. The on/off seems to be happening quickly, like within a minute or within even seconds at a time.

 

[Gieser]

Continued from above... (sorry that these are long)

I thought of one other thing. The compressors have 3 diferent time gaps. 1/90 - 8/92 FJ80, 8/92 - 5/93 FJ80, and 5/93 - 1/98 FZJ80.

Would it matter if the compressor or clutch were not the EXACT parts needed for the system? Below is the reason I am asking.

The first compressor I ordered (I ordered them from Toyota and with a new clutch) was the wrong compressor. I did not realize this until I looked at the clutch and the pulley that came with it. The pulley was for a serpentine type belt, but my make (2/93) is a v-belt style. The clutch also had a very short connection wire and my make needed a longer one that stretched to the rear of the compressor. I called my parts guy and he ran the parts against the VIN and he had ordered the wrong parts. Took them back and got the correct parts and this compressor looked exactly the same, but was the correct one. The clutch had the pully it needed, the magnetic part of the clutch hat the longer wire to reach to the rear of the compressor, and the clutch plate was new. Set it all up and charged the system and trhe compressor was dead . I left it at the shop and told my parts guy to go ahead and oreder another one and he delivered it to the shop. Whew, now you are up to date with why I am going to ask this question...

I noticed last night while checkin everything myself that the clutch from Toyota was like the first clutch I received with the short cord and the pully and clutch plate were from a used (my old) compressor, so that alerted me that the reason they had to use the old was because the pully was for a serpantine belt. I asked them and they told me they had to switch it out. I am thinking that if it were not the right part, maybe the readings for the A/C Amp were not what they needed to be. Just another thought.