another A/C problem

[7M-KDL]

so i have a retro fitted compressor. i recently recharged the system. wehn the car is parked the ac will work fine. it is nice and cold. when i drive around town at about 45-50mph, whether im in 4th or 5th gear the ac still blows nice and cold between 42*60*. here is where the problem comes in: when im at highway speed or higher in 5th gear (60-65mph) the ac will not blow cold air, the the temp goes up to about 80*F(i have a gauge in my blower vents). even though i am turning the same rpms as i am in 4th gear at 50mph. anyone else have this problem? i tried searching but maybe im not good at using the search. thanks in advance for any help

 

[mkiii222]

Using recirc or fresh air?

There isn't anything in the ECU / AC system that would change based on gear.

If it's recirc than it's probably just the speed of the incoming air not allowing it to get cold enough. I only use 'outside air' to initially cool the car from being parked in the sun, then I switch to recirculated once the car's cooled enough which is normally by the time I'm leaving the parking lot/getting to the end of my subdivision.

80 F still sounds a bit warm though, but again I stuck with R12 and could care less for R134a. Maybe the cooling unit needs to be cleaned out/replaced?

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=AC&P=8

 

[rayall01]

Using recirc or fresh air?

There isn't anything in the ECU / AC system that would change based on gear.

If it's recirc than it's probably just the speed of the incoming air not allowing it to get cold enough. I only use 'outside air' to initially cool the car from being parked in the sun, then I switch to recirculated once the car's cooled enough which is normally by the time I'm leaving the parking lot/getting to the end of my subdivision.

80 F still sounds a bit warm though, but again I stuck with R12 and could care less for R134a.

Recirculated air gets colder faster, because as the air gets colder, it gets RECIRCULATED, and cooler air passes over the heat exchanger, which makes it colder, and so on, and so on, and so on. Outside air is consistently hot, and will only cool so much as it passes over the heat exchanger only once, and the passes into the vehicle in a semi-cooled state. Recirculated is COLDER! End of story.

 

[7M-KDL]

Recirculated air gets colder faster, because as the air gets colder, it gets RECIRCULATED, and cooler air passes over the heat exchanger, which makes it colder, and so on, and so on, and so on. Outside air is consistently hot, and will only cool so much as it passes over the heat exchanger only once, and the passes into the vehicle in a semi-cooled state. Recirculated is COLDER! End of story.

thanks for both of your answers...maybe mine is always on fresh. rayall, im a littl confused by your post though, wouldn't higher speed cause the air to be cooler? maybe im misunderstanding the mechanics of the system..

 

[mkiii222]

If it's recirc than it's probably just the speed of the incoming air not allowing it to get cold enough.

This is what Rayall meant, it was a simple mistype.
It should read: If it's 'outside air' than it's....

And the speed of the air doesn't make it cooler. Think of a warm breeze, it's still a breeze but it's hot air.

Think of the air going through the 'cooling unit' like you would think of coolant going through the radiator. The faster the flow the less heat transfer occurs.

 

[7M-KDL]

This is what Rayall meant, it was a simple mistype.
It should read: If it's 'outside air' than it's....

And the speed of the air doesn't make it cooler. Think of a warm breeze, it's still a breeze but it's hot air.

Think of the air going through the 'cooling unit' like you would think of coolant going through the radiator. The faster the flow the less heat transfer occurs.

alright...makes sense i think...ill have to test the theory, i hav 88 climate control..which is recirc which is outside?

 

[mkiii222]

alright...makes sense i think...ill have to test the theory, i hav 88 climate control..which is recirc which is outside?

The one to the right of A/C that looks like a car with a looped arrow. When the light is on/button is in, it's on recirculate.

 

[7M-KDL]

The one to the right of A/C that looks like a car with a looped arrow. When the light is on/button is in, it's on recirculate.

cool thanks. ill see if that changes anything.

 

[7M-KDL]

i had a chance to test the recirc theory but to no avail. im not saying that recirc isnt colder but it did not sold my problem. when im driving around town the ac blows at about 50* but then when i get up to highway speeds, like 59, 60, 65 it blows warm, around 80*. does anyone have any other ideas as to why this might be happening? PLEASE HELP :1zhelp:

FFFFUUUUU.....

 

[Who]

Your evaporator might be freezing up or turning into a block of ice. It happens on my Ford Exploder when I drive on the highway for more than 30 minutes. Try turning off the compressor for about 5 minutes with the fan running and then turn turn it back on and see what happens.

 

[rayall01]

Your evaporator might be freezing up or turning into a block of ice. It happens on my Ford Exploder when I drive on the highway for more than 30 minutes. Try turning off the compressor for about 5 minutes with the fan running and then turn turn it back on and see what happens.

Yeah, I forgot about that possibility. That can definitely cause the symptoms you describe. When it starts happening, immediately pull over and check all the visible AC components. If something is frozen, it should be visible. P.S. leave the car running and the AC on then you check.

 

[7M-KDL]

alright, thanks guys, ill check that next time.. but let's assume that is the problem, how do you go about fixing something like that?

 

[rayall01]

alright, thanks guys, ill check that next time.. but let's assume that is the problem, how do you go about fixing something like that?

In my experience, not Supra specific, a few things can cause the issue. Bad lines, leaks, and undercharging come to mind. There maybe other possibilities as well. You should take it to someone who's an expert in AC repair.

 

[anonymic]

What does anyone think about water in the system? High enough ambient humidity when the system was put together, or if the system was left open for any length of time could let in enough water to freeze at the expansion valve.

 

[rayall01]

What does anyone think about water in the system? High enough ambient humidity when the system was put together, or if the system was left open for any length of time could let in enough water to freeze at the expansion valve.

Slim, remote possibility, as the dryer should have removed any moisture. Unless his dryer is bad.

 

[7M-KDL]

What does anyone think about water in the system? High enough ambient humidity when the system was put together, or if the system was left open for any length of time could let in enough water to freeze at the expansion valve.

where is the expansion valve? im still having multiple problems with my a/c. not only does it get warm at highway speed i also have a large leak apparently. by large i mean i filled the system last saturday and it was empty on thursday afternoon. i put uv dye in but the only place i can see it is where my retro fitting is. how tight should that fitting be?

also, i checked cygnusx and for my problem is says thermistor(under troubleshooting) it isnt for my exact problem but similar. the symtom they use is "limited cool air" at high speed while mine has "zero" cold air at high speed

 

[jetjock]

Maybe it should be tight enough to prevent leaks? And the system shouldn't even run if it's empty. If it is you're about to be in for some very expensive repairs...

 

[7M-KDL]

Maybe it should be tight enough to prevent leaks? And the system shouldn't even run if it's empty. If it is you're about to be in for some very expensive repairs...

well i put it on there tight (what i thought was tight anyway)will it bottom out, i dont want to strip it. and it doesnt run when its empty...but, after i had just filled the system it didnt blow cold air at highway speed. then it stopped blowing cold at all (later in the week)so i checked and the system was "empty"

edit: is the "in-car" sensor mention/pictured in the tsrm where those two small holes are in the passenger side dash(just above the Glove box) i think its called the no.3 instrument panel register in another section

 

[jdub]

Wrong section for this question...7M-GTE Tech is for turbo motor specifics. Thread moved...please pay attention to where you post.

 

[7M-KDL]

Wrong section for this question...7M-GTE Tech is for turbo motor specifics. Thread moved...please pay attention to where you post.

oh, my bad, i figured that since its possibly a problem with components connected to the gte this is where it would go. i didnt know if there was a difference between the ac system on na and turbo. but thanks i guess..any ideas about whats causing my problem?