I have a 93 RX-7, and was wondering if any of your guru's has some advice. The question is why it only blows hot air regardless if the AC is on or not. I think the heater door is stuck open, but I haven't taken anything apart yet...

 

Are you sure the system is charged?

 

The system was converted to r134a and I can see freon in the sight-glass, it may not but 100% charged, but it almost begs the question. Whether I have the A/C on or not and no matter were the temperature is set I am blowing hot air, even if it is like 50 outside... I should have been more clear :-(

 

The reason I ask about the system being charged is that it has a failsafe to stop the A/C functionality if the freon level is low (to make sure it never runs the system completely dry). IIRC, there is also a fuse for the A/C system. Verify that the fuse isn't blown.

 

Nah the low pressure sensor isn't tripped, and the compressor isn't even cycling, it is just running when I turn it on... I am going check all the fuses, but the air gets marginally cooler when I turn the A/C on.

 

Then that's an indication that your system needs to be fully recharged. And don't try just adding 134a. Do it the right way. Have the system completely evacuated to suck all the moisture and air out of the system, then have it recharged.

 

That is a thought of mine, but it doesn't answer the question of why when I have the A/C off, and the temperature turned all the way cold, why I don't get ambient temp air...

 

I wonder if your problem is in some way related to the heat problem so many of us suffer from -- that even when the heat is on maximum and set to blow through the footwell and defrost vents, it's only marginally warm at best (despite the coolant system and motor being completely healthy).

I've suggested in the past that the actuation of the door that controls the amount of air passing through the heat exchanger may not be operating fully in either direction, resulting in neither max heat nor min heat. It could completely be possible that your heat is on while your AC is on as you say. I often feel hot air coming out of the vents with the A/C off and the heat turned all the way to off, even when the ambient temperature is low. I believe there is merit to your theory but no one has yet to provide any hard evidence.

 

One other point....IIRC 134 will not get as cold in the R12 system because it's designed to operate at higher pressure.

 

I agree that the door actuation, and movement are a problem on our cars. In my case, I get no heat. The AC works fine. I checked the FSM to see what to do. It suggested that the dash needed to be pulled out to fix the problem.

 

This is very true, and if the shop that converted the car didn't change the mineral oil for the r12 out for pag oil which the r134 needs, then you get almost no room for the r134 to boil, thus no cooling...

I am going to get the gauges hooked up on it tonight, just wanted to know if it was a common problem :-(

All the fuses look good, I cannot find anything out of place. I am going to be putting a remote start on the car, so seeing as I will be under the dash anyway, i might give me the ducting a look....

 

Did you ever solve this problem? This is really tiring in the summer. I get hot air on my feet no matter what I do.

Thanks in advance,

Art
90 Vert DC