Overheating issues

[IBoughtASupra]

How much vacuum did the system hold when he was evacuating it? If it doesn't hold usually 20-24, there is probably a leak.

Mine went to 24 when I was evacuating it before charging it up. It is not as cold as I would like it but with that said, I have a huge intercooler though.

 

[jetjock]

He said it pumped down to around 29 and held. I hope they pumped it again at the shop though. If I were him I would have charged it myself but based on what he reports it seems to have been done correctly.

24 is terrible...

 

[CyFi6]

Ya it held a little more than 29" overnight just fine. They pulled a vacuum on it again before charging it. I guess that is that then.
I really need to face reality and get a summer car or something, daily driving the Supra out here in the summer really isn't working out like I had planned, there is just too much heat. After coming off the freeway with the AC on high etc and coming to an idle for an extended period of time, the temp gauge started rising up too. Heat coming off the pavement is ridiculous, I don't think the car is set up for this kind of heat, at least that's the impression I get from my/other peoples experiences.

 

[CyFi6]

Wow this thing really blows ass! I wish there was an edit>undo button for expensive parts purchased. After coming out to my heatsoaked car I went to the drive through and waited about 10 mins for some food blowing 65-70 deg F on medium fan at idle...meanwhile all these losers relaxing in their cars with the windows up AC blasting cold air at their faces...FML! Also noticed my aux fans come on a lot, and those only come on when high side pressure is above 275.

 

[jetjock]

Bummer. Have you put the gages back on it?

 

[CyFi6]

Haven't had much time, so I haven't. Plus I am going out to California for a bit where it should actually work decently well, hopefully I wont really be concerned about it over there. If I've got time I will put the gauges on it when it's really hot out and not blowing cold and report back. My foam insulation that I put around the suction line by the exhaust melted , and the foam I put under the condenser decided to get sucked in between the condenser and radiator, so I guess I will pull those things out haha.

 

[grimreaper]

I walked away from my hunt for the coldest ac at idle quest. My conclusion was there is just not enough airflow at idle with 120-130 degree asphault temps baking the underside of the car. I found the gauges to be deceiving when monitoring them too. The hoods open, your most likely not in the sun etc.. It always performed greeat at idle with the hood open!

I used to compare the supra ac to more modern ac systems. I had to stop that when I realized the ac system was essentially the same, but the car it was in was very different. Elec fans, more ground clearance, lager bumper openings, smaller motor, larger motor, bigger condenser, parallel flow etc.. oh and different freon.

Have you checked with jdub to see if he has mastered the arizona heat + supra ac?

 

[Nick M]

Steady Cruise
Low pressure - ~8 psi
High pressure - ~200 psi
Vent temp - 45 Deg

Coming to an idle
Low pressure - 30 psi
High pressure - 295 psi
Vent temp - 52 Deg

2500 RPM stationary
Low pressure - 8 psi
High pressure - 260 psi
Vent temp - 48 Deg

Then I parked the car outside for about an hour and took off... This is after 10 minutes of driving
Low pressure - 8 psi
High pressure - 240 psi
Vent temp ~62 Deg...and rising if coming to an idle.

When I went to pay, the tech reported 40 PSI low side and 210 PSI high side with 62 degree vent temp. I told the cashier that the low side pressure seemed high and that spec was about 20-28 PSI.

So you got rid of the low side restriction. How good is your blower motor? This sure seems like you had more than one problem, but couldn't see both because of the restriction.

I really need to face reality and get a summer car or something, daily driving the Supra out here in the summer really isn't working out like I had planned, there is just too much heat. After coming off the freeway with the AC on high etc and coming to an idle for an extended period of time, the temp gauge started rising up too. Heat coming off the pavement is ridiculous, I don't think the car is set up for this kind of heat, at least that's the impression I get from my/other peoples experiences.

A SUV has a huge radiator and condensor and can shed heat much easier. This is true.

...FML! Also noticed my aux fans come on a lot, and those only come on when high side pressure is above 275.

The water temp switch also will turn them on. Scaled your airflow meter to raise overboost fuel cut?

 

[CyFi6]

I walked away from my hunt for the coldest ac at idle quest. My conclusion was there is just not enough airflow at idle with 120-130 degree asphault temps baking the underside of the car. I found the gauges to be deceiving when monitoring them too. The hoods open, your most likely not in the sun etc.. It always performed greeat at idle with the hood open!

I used to compare the supra ac to more modern ac systems. I had to stop that when I realized the ac system was essentially the same, but the car it was in was very different. Elec fans, more ground clearance, lager bumper openings, smaller motor, larger motor, bigger condenser, parallel flow etc.. oh and different freon.

Have you checked with jdub to see if he has mastered the arizona heat + supra ac?

I hear ya, I realize the old Supra has its limitations, but 70 degrees at idle out the vents is kind of depressing. You are from Houston, you probably know as well as I do that 70 degree air isn't going to do crap when you have 105+ air outside plus full sun.

So you got rid of the low side restriction. How good is your blower motor? This sure seems like you had more than one problem, but couldn't see both because of the restriction.

Blower motor pushes enough air, only problem is it is warm air. The higher I set the blower speed the warmer the air output.
If there are other problems, they are not refrigeration related (assuming nothing I replaced was defective), as everything in the system has been replaced minus the two hard lines along the front/passenger side of the engine bay, and those lines were flushed.

After you quoted those numbers, looks like my AC worked better before than it does now. I have a hard time getting the vent temp below 55 driving around town (on medium blower), and coming to an idle it just rises from there. The problem is the vent temp rises faster than it falls, so every time I come to a stoplight the vent temp rises a bunch and takes a lot of steady state driving to get it back down. When most of my driving is city/stoplights at every block, this can prove to be irritating.

The water temp switch also will turn them on. Scaled your airflow meter to raise overboost fuel cut?

My car for whatever reason does not turn the fans on due to coolant temperature. There is no water temp switch, and there is no plug on the harness for it. This might be because it is an 86.5, not really sure. The fans only operate if the AC is on and the high pressure switch is closed (seems to be around 275 PSI), doesn't matter how hot my engine is, if the AC is switched off the fans turn off. I am running MaftPro speed density with 550cc injectors, so the airflow is scaled back a bit.

Going to put the gauges on when I get home from work, but its going to be night time/lower OAT's. I will post the results.

 

[jetjock]

I'm sure lots of owners have/had adequate AC performance in such climates. The car was after all the company's flagship. I've never had mine in PHX but summer in Vegas and the Mojave was never a problem nor was climbing the Sierras.

I forget, does the car have electric fans or the stock fan/clutch?

 

[CyFi6]

I'm sure lots of owners have/had adequate AC performance in such climates. The car was after all the company's flagship. I've never had mine in PHX but summer in Vegas and the Mojave was never a problem nor was climbing the Sierras.

This is the problem, I have never seen/felt that for myself. What I have seen for myself is other Supras which have AC as bad as mine. All I know is that people tell me it should work better than it is, yet I have no proof that it actually can. Arizona Mobile Air, basically one of the most well known AC shops in the valley suggests that the car has a weak/poorly designed system. After all, they sent me off with 62 degree vent temps with the hood open and engine at 2000 in the shade, any conditions less ideal than this (basically all my driving situations) would then yield higher vent temps. If other Supras are performing better than mine out in this heat, they must be touched by god or something because mine is cursed otherwise.

EDIT: I re read your comment. You said "adequate AC performance", not "good AC performance". Technically speaking, a 20 degree drop in temp from ambient (2" in front of the condenser) is adequate. In that case, when I jump in my car and it blow 80 degrees for the first 5 minutes, even then it is adequate.

I forget, does the car have electric fans or the stock fan/clutch?

Brand new OEM clutch fan with all air dams in place (hood seal, shroud, engine undercover etc). I think you know me better than to rule out an aftermarket electric fan as a possible cause . Only things aftermarket in this area are my Koyo aluminum radiator and my 3" inter cooler, but saw no difference in AC performance before when I had the stock intercooler, was pretty crappy with either one in place.

 

[IBoughtASupra]

We had a problem like this on a maxima and it turned out to be the expansion valve.

Did you replace that? Condenser replaced too?

 

[gurley0916]

Curious to know why the expansion valve would do this? Im having the same issue with my car and im in 90 degree weather

 

[CyFi6]

We had a problem like this on a maxima and it turned out to be the expansion valve.

Did you replace that? Condenser replaced too?

Here's a list of everything that was replaced going in order of flow through the system lol
Compressor
Discharge flexible line
Condenser
Receiver/Drier
Expansion valve
Evaporator
Suction flexible line
All seals
Hardlines flushed
Fan clutch
Fan shroud
Fan blade (10 blade)
And all of the above are BRAND NEW OEM parts minus the compressor which is a remanufactured unit. Unfortunately, I have run out of things to replace....

 

[jetjock]

I stand corrected on the fan. You're right, I should have known better

I feel for ya. It sucks to have gone through all that and end up no better off. There's always the performance test in the TSRM. That should put to rest whether it's cooling as designed based on the test conditions but with the low side that high I doubt it'll pass.

Edit: 62 degrees in the shade at 2000 rpm is a broken, not poorly designed, system. I know AMA is supposed to be one of the best but there's no excuse for that.

 

[IBoughtASupra]

Do something while running the car with the A/C on.

It an old trick, with the car on at operating temperature, turn on the A/C and start soaking the condenser with cold water. It should keep the pressure down. Report back after you do this. Don't just spray a mist on it, soak the thing down, as in, no fitting on the end of the hose, just wide open.

I didn't see if you replaced the stock condenser fan. Did you replace it? Stock intercooler or upgraded? Lastly, I have seen this SAME problem with all of what you replaced on the same Maxima stated earlier. I am not sure if the expansion valve has an adjustment on it as I have not seen a Supra one but the NEW expansion valve came adjusted wrong. The screw was in too much and caused poor circulation of the refrigerant but the gauges showed decent readings.

 

[CyFi6]

I just put the gauges on it, keep in mind this is with a relatively cool car and it is night time, with OAT between 90 and 100.
Low PSI: ~25
High PSI: ~265
Vent: ~59 deg
RPM: 1500
Fan: High
Mode: Recirc
Windows open

Funny how the TSRM gives no mention of what vent temps should be.

I know what you are saying IBAS, with the hose thing. Couple problems though, first is that I dont have access to a hose, lol. Second, drenching the condenser would probably drop my high side pressures a lot, but what would that prove? There is no way a clutch fan can bring condenser temps down as much as flowing water. And if it does significantly increase the performance with water on it, what would the solution be? I have nothing else I can do to increase airflow through the condenser, the fan already sounds like a semi truck as it is.

 

[IBoughtASupra]

You have no recharged the system since to left that A/C place, right? I believe they put too much gas, that will also cause this as the condenser will not be able to cool the refrigerant efficiently.

 

[jetjock]

The low side is 25 with a vent temp of 60 and that doesn't strike you as strange? What is the resistance of the evap thermistor under those conditions?

 

[CyFi6]

It does strike me as strange... but its exactly what I was experiencing before! High superheat. My high side pressure is WAY out of spec also... 265 PSI when it should be no greater than 210 PSI. Maybe this high high side pressure is causing the weirdness on the low side (I am not sure how high high side pressure affects low side pressure. I had one guy tell me I need to bring the high side pressure down and the low side pressure would subsequently come up). I also don't understand how the tech got 40 PSI on the low side, I am reading nowhere near that unless I am idling. I just put the glove box back on, I will see if I can access the thermistor.

Apparently the low side number doesn't strike any of the guys on the ac forum as strange either because he still insists it is my intercooler. Not to mention, in their eyes, the system is functioning fine. I am liable to rip my hair out one of these days.