Summer has arrived and I have a question about my A/C. In average temperature, my A/C can get extremely cold. We had a heat wave recently, upper 90's and my a/c has not worked well in it. As soon as it cools down it works well again... I noticed a rad hose was bumping the large a/c line that goes to the firewall and melted part of the factory insulation. Can just insulating the lines fix my problem? What should I use to do that? I have an 89 (VG) with factory R-12

 

This is most likely caused by the dash temperature, since recirculating air is drawn through the vents under the windshield.

 

which explains how come defrost disables recirculation? b/c they are the same vents? if so i never knew that... i always wondered where the return vents were.

 

I didnt know that either, i always wondered about recirculating air.

Would it be more beneficial in extreme heat to not recirculate?

I have a black dash and black leather interior, so it is definately hot inside

 

So after your guys' answers I went to look at the diagrams, and now I dont think I was right about where the air is drawn during recirculation.

Gotta go look at the car and figure it out, but the intake unit sits to the right of the cooling unit, and it is what switches input between outside and inside air.

 

Make sure that your heat is actually turning off!

The most frequently overlooked issue with A/C temps is that the heat is on when you think it's off. If the heater core is getting hot it doesn't matter what temp your A/C runs at.

I just recharged my I30 to find out that my heat is intermittently coming on and seems to want to do it more when it's hotter outside.

 

That should be caused by the mix door which makes air pass or bypass the heater core, which is always at engine coolant temperature.

 

Yeah, I know. I just gotta get in there and find out why it keeps doing it. I'm tempted to just bypass the heater core until winter!

 

okay there's a couple things i noticed when lookin in the fsm.
there's a switch for the cold side called: cold max switch.
what this does is open a small door which for some odd reason makes the air even colder.
also it send the signal to a small "module" and what this does in turn activate the solenoid to close the water valve.

OR IT COULD BE:
the vacuum hose came off the water valve and it's lettin more coolant through the heater core than normal.

happened to me before.

 

i was thinking the water valve is an on/off operator.... but it could be stuck open if the hose is off. i forget its 'natural state'. but it's certainly a good idea to check that.

 

Thing is, it only happens in extremely hot weather. During warm weather I can freeze my behind off

 

I'm thinking the max cold switch myself.
FWIW I have a donor control head in the garage (bad slider)

 

Mikekantor was definately right. The difference in temperature between the floor vents and the upper vents is very large. So my cooled air is being reheated as it goes out the upper vents. Other than parking in the shade, is there any way to avoid this?

 

well i noticed with the recirculatin air was waaaay cooler than the air being pulled through the windshield.

 

rice it out and paint everything white

 

aside from the anti-rice factor, there is a good reason not to paint your dash white: white will create a major glare on the dash, blinding you while driving, on a nice sunny day.

window shades, such as the ones that go in the windshield, placed in both front and rear windows, the pull down ones, for the side windows, all will help reduce sunlight super-heating the inside of the car.
they have solar-powered fans that supposedly pull hot air out of a parked car, are UN-recommended, because independent test have shown little-to-no change, and are a leak and burglary hazard.(sorry, no links yet, to confirm that statement..)