MK3 AC Performance ? or Alternator problem?

[sayedco]

Dears,

I bought my MK3 1990 Supra recently, it's got a 1JZGTE swap with it’s original R154 Transmission, the AC was not cooling, so I went to an AC repair shop, they detected a leak on the compressor, so they changed the seals on it and it got working, they also changed the dryer, filled it with enough regrigerant.
Then it was have ok temperature, but not cool air, he said that my aftermarket radiator is very thick it’s blocking the condenser, so I installed an Aux Pusher fan on the condenser, got a little bit better on highway and when I raise the RPM , still not cool.
I noticed few things:
1- It is better at night when the climate is less hot (in the morning it’s 109 F , reaching 115 F at noon. The AC doesn’t do anything at this peek time and in the sun.
2- The blower when on High, it doesn’t push much air, I have to raise the RPM for it to push enough air, also I noticed the headlights are dim when the RPM is low, when I raise it, the headlights become brighter, the blower pushes more air, the electric after market fans go faster.
Do you think it has anything to do with the alternator ? can it affect the AC cooling performance because of it’s low performance and inability to power all accessories like the 3 electric fans?

or is it that the MK3 Supras AC system is hot anyways ? it's not normal, i just ordered an IR thermometer and an AC vent thermometer to give you guy exact numbers.

 

[fox74]

You have to check the pressure on high and low side of the A/C system, the high side is around 212 psi and very much constant if the compressor and duel switch are doing their job, and and low side is around 45 psi and go up and down a bit based on cabin temp. This is the first step, what A/C shop told you is pure BS, the people who designed the car did knew what they are doing. As for the fan rpm, the lower the rpm then the cooler the air should get because the flow rate is reduced. in %99 of the time problem is expansion valve with supra specially if the A/C system has not used for awhile. As for your lights dimming, the fact that they get brighter as you rev the engine indicates your alternator is working, check your battery voltage with car off and lights on, if it drops below 12v may be your battery needs to be replaced. finally the vent temp should be around 60F

 

[Nick M]

he said that my aftermarket radiator is very thick it’s blocking the condenser, so I installed an Aux Pusher fan on the condenser, got a little bit better on highway and when I raise the RPM , still not cool.

Most of that post is hilarious and shows how the industry is going to collapse from a lack of competence. If he gets 212 and 45, even in 115, that is high and his discharge temps will not be so great. The TXV should be about 25 psi. I can take it that was a typo.

 

[fox74]

Toyota shop repair manual states high pressure side 199-220 psi, the low is a bit tricky because depends on ambient temp and relative humidity but it states 30 psi@32F, mine reads between 40-45 psi if I remember correctly.

 

[sayedco]

Thanks guys for the information and help.

I just came back from few garages , the last two technicians hooked the gauge on the low side and it was reading 80 PSI, they said it's a weak compressor. ambient temp was 104F

Is there any chance it's not the AC compressor? i just wanna be sure i don't change it and the reason is something else. Thanks.

 

[CyFi6]

Only knowing the low side pressure is 80, its impossible to say if it is the compressor or not. It could be, but theres a lot of other things it could be like simply too much refrigerant. Need more information. What was high side pressure?

 

[sayedco]

Only knowing the low side pressure is 80, its impossible to say if it is the compressor or not. It could be, but theres a lot of other things it could be like simply too much refrigerant. Need more information. What was high side pressure?

Thanks,

Looks like i'm gonna buy a set of gauges and test myself.

 

[SupraClaou]

Take the car to a good car A/C service shop to properly clean the A/C system, make the proper vacuum and check for leaks.
Then if all is ok with no leaks, they should fill the system with 650 grams of old R12 or new R134a refrigerant which is what Toyota indicates for the mk3 Supra.
Then turn the A/C on at the medium blower position and in the non fresh-air mode.... and let it operate for 15-20 minutes. It should operate for that much time now if it hasn't operate for years. In the mean time take a water hose and blow water over the condenser with moderate pressure to take away all of the small particles , debris , and dust...
After that, and after 20 minutes of operation take an accurate temperature gauge that all the A/C shops have (it should look like a pen) , and put it in the vent which is near the
digital in dash clock. The gauge should read at least 60"F vent temperature.
If still you don't get that temperature, replace the expansion valve which is located in the evaporator box which is located behind the glove box.
If you look at the R12 conversion to R134 sticky thread , it says how to change that valve.
A GOOD WORKING CONDITION AND PROPER IN-CAR A/C SYSTEM SHOULD READ AROUND 50'-55'F (at least 60'F).

Please take your time and do the following steps..and let us know the results. Good luck resolving the A/C issue.

 

[sayedco]

Take the car to a good car A/C service shop to properly clean the A/C system, make the proper vacuum and check for leaks.
Then if all is ok with no leaks, they should fill the system with 650 grams of old R12 or new R134a refrigerant which is what Toyota indicates for the mk3 Supra.
Then turn the A/C on at the medium blower position and in the non fresh-air mode.... and let it operate for 15-20 minutes. It should operate for that much time now if it hasn't operate for years. In the mean time take a water hose and blow water over the condenser with moderate pressure to take away all of the small particles , debris , and dust...
After that, and after 20 minutes of operation take an accurate temperature gauge that all the A/C shops have (it should look like a pen) , and put it in the vent which is near the
digital in dash clock. The gauge should read at least 60"F vent temperature.
If still you don't get that temperature, replace the expansion valve which is located in the evaporator box which is located behind the glove box.
If you look at the R12 conversion to R134 sticky thread , it says how to change that valve.
A GOOD WORKING CONDITION AND PROPER IN-CAR A/C SYSTEM SHOULD READ AROUND 50'-55'F (at least 60'F).

Please take your time and do the following steps..and let us know the results. Good luck resolving the A/C issue.

Thanks a lot !

I have that temp gauge pen, currently the lowest i get is 70F, i'm gonna do what you mentioned when i find a good AC shop and i hope i get it fixed. Thanks again.