Air Conditioner LJ78

[everbret]

Another question re: 1991 Prado LJ78 2L-te.

When I originally got the vehicle, I tried the air conditioner and it would occasionally work. I could hear the click of the switch in the dashboard when I turned the airconditioner knob, then I would get the increase in revs and finally cool air would stop blowing. This would work on and off with jiggling of the switch, but finally, it was no more. Now I can hear the click of the switch in the dash, but no increase in revs and no cool air.

Any ideas?

Also, if I don't get it working, would I get any benifit in mpg from removing the air-conditioner fan belt?

Thanks

 

[Radd Cruisers]

Your system pressure is probably too low to work. Best bet is to get the R12 drained out and then your system re-fitted for R134a.

Just a note that AC work does not typically come cheaply.


~John

 

[dberwin]

I had mine recharged last year and it was expensive. BC interior is often 40 deg c so needed it. I can tell on long hills and watch temps (even closer) when it is really hot on the hills. You can tell with it off it has more power but almost all four cylinder cars can tell. The extra load and full core in front of radiator effects heating.

If you are not fixing it and removing things get rid if the AC core in front of the radiator. This would be the biggest impovement.

 

[everbret]

dberwin,

What did you end up getting it recharged with? Did you have to get it retrofit for r134a? Or, did you use one of those alternatives? How much did it cost?

Cheers

 

[Gun Runner 5]

LJ78 A/C

The previous owner of my Lj78 did not use the A/C however I will need it this Summer so I took it in to get it recharged and converted from R12 to 134. After the recharge the unit would still not work ( and yes I can hear the "click" in the dash.) but the tech says that means nothing and the remedy is replacing a pressure switch under the dash. I should pick up the Cruiser tomorrow and I will be glad to post the results as well as a parts list. ............1978HJ45

 

[crushers]

R134 isn't as cold as the R12 and if you shop around there are some shops that still install the old R12...although they do not publisize it.
read illegal.

personally, i use the 2/90 coolant

 

[dberwin]

I used what crusher said (origional) and it cost about $300 and there was a leak so finding that was included. Just an O ring.

 

[Gun Runner 5]

I got my 1990 LJ78 back from the A/C shop today and the airconditioning systems now blows cold. My A/C "on-off" switch no longer worked even though it still made the clicking sound when cycled. This switch was replaced with a toggle switch next to the original switch. The other problem was the thermostat which no longer worked and was very difficult to access so is was replaced with a pre-set unit that should keep the temp. at a comfortable level. One low side / one high side fitting combined with 1.8 lbs. of R134a and the A/C was good to go. I am not recommending that you do it this way however in my case it was the best route to take. ......1978HJ45

 

[Rummat81]

AC diagnosis

Hello Guys,
trying to keep information in the same thread.
I am reconditioning my R12 AC system after it stopped working for about 2 years. I have done the following
1. Rebuilt the compressor with new Orings and shaft seal.
2. pressure tested the system with 60 PSI and checked with Vacuum. Holds vacuum.
3. New Orings and mineral oil.
4. wasted 2 cans of refrigerant to a wrong sized oring on the high side. changed that and pressure tested.
5. Took the evaporator out and gave it a good cleaning.

I would like to know the operation of the low pressure switch. How to check that it is working properly.
At uniform 60 PSI pressure (both high & low) filled with Air ( i know not the best way to do it), should the compressore kick in. I can short the switch and the compressor comes on with engine revs etc.
Can i check for continuity or resistence?
At What pressure should the compressor kick in?
I am using the duracool product for R12. and I have a AC manifold guages and venturi vacum pump ( for what its worth )

Thank you All,
Ali C.

 

[Radd Cruisers]

There is a pressure switch near the evaporator in the AC housing that will go from time to time - most likely your problem.

~John

 

[Rummat81]

Hi All,
After all i got the AC to work. ( well there are still some issues). The Low pressure sensor was shot. You were right John. Marks auto Air on 59 Ave and 92 street provided me with the sensor Santech part # MT0374. its for an 88 toyota truck. EPC # 88645-12020. Toyota wanted $80 for it, i got it for $30. The Santech part says Honda and R134 but not to worry. Mark is a wonderful guy to deal with and for those who know its near by 4Wheel auto.
I am reading close to 55 PSi on 15'C days, i just put one can of Duracool just to check the system out, and to not waste more, if there are any leaks.

Now the problem, the AC idle up works only in park and Neutrral. as soon as i shift into reverse or Drive, the power to compressor is cutoff.
The Ac compressor control box apparently monitors the engine RPM as well. I wonder what is going on there.
Anyone got any ideas.
Thanks everyone.

 

[Rummat81]

as suspected it was the remote starter wiring,
the two starter signal wires were crossed together, blocking the signal to the AC amplifier. i cut the remote starter loose for now, and the AC is working fine in All gear positions.
Thank you all for your great help,
Ali C.

 

[everbret]

Had you installed the remote starter? Or is that something standard for these vehicles?

 

[Rummat81]

The vehicle came with a remote starter module, although i could not use it. the way it was spliced into the steering column harness, it looked like factory/dealer option with plugs and everything.
I then installed a new remote starter of my own and had crossed the two orange,orange/black wires to my remote starter.
Never tried the AC up until now.
the just cut and taped the wires coming to the remote starter from the plugged in harness, so electrically, they are just like factory now with no splicing etc.
The AC and the other electrics work fine now.

I am going to try to reinstall it again, and try things a bit differently.