So, last summer I noticed that my passenger side doesn't get cold when I turn on the AC, it just always maintains outside air temperature. I was kinda okay with that, just select recirculate or close the two passenger side vents.

Now, this summer, it just got warm enough that I need to use my AC and it's a nightmare. After several minutes of nice cold air blowing through the vents, all of a sudden HOT AIR, not just air with outside temperature, but HEAT blows through the vents for about 5 - 10 seconds, and then back to nice cold air. I don't know what's wrong

It's like I'm in the shower and then someone flushes the toilet, very bad!! Any ideas? Btw, it's a 99 GS 300.

 

Make sure the air is circulating within the cabin.

Our cars are gettin' old, so you may need a recharge.

 

Sounds like you're running low on freon. Recharge the system and you should be good. If you get it done at a good shop, they should run dye thru the system to check ensure there are no leaks.

 

i had a similar problem. i checked my cabin filter and it was really dirty. bought a new one on ebay and replaced it. and now it gets cold in seconds and stays cold the whole time!

 

Car ac systems use a blending door/flap to mix the proper amount of air from the heater core and the evaporator to get the right temperature out the vents from these hot and cold sources. Sometime vehicles can have issues with the control for the blend door and the temp may flucuate wildly since you may be getting a sudden blast of heat from just the heater core.

But check all the obvious first, like cabin filter make sure it is clean, when I got my car I pulled mine out and it was almost completely clogged with dirt, paper receipts, leaves, and lint/dust/fuzz...

Need to put a set of gauges on the hi/lo and you can tell pretty quick if the compressor is bad or your low on freon, etc.. Try to pay attention to the ac compressors clutch engaement and see if you can tell if it is 'on' when the hot air is coming out.

If it needs a recharge then there is 100% a leak. Freon systems are indefinite until a leak develops. (not counting mechanical breakdown of compressor, expansion valve, etc..)

 

Take it to your nearest firestone they will put dye in your system to find a leak and recharge your freon for $100+- it's an overnight job if done right.

 

Thanks for all the input; I had noticed that whenever the problem occurs the car actually throws itself in front defrost mode (even though the dash display is still showing straight to face blow). And then just now when I get off for lunch, I get in car and as soon as I start it up it defaults to heat and front defrost, regardless of what the display is showing. I have tried cycling through all modes and temperature ranges but car is stuck in full heat blowing through the front defrost vents. I might end up just pulling the heater fuse until winter time then

Any thoughts? It's a 99 GS 300.

 

how do you change cabin filter

 

cabin filter is behind glove box
you have to open glove box pull old filter and put new one (very simple)

 

Anyone find a solution since my gs300 is doing this also. Everything has been changed from expansion valve, compressor, condensor and evaporator. it has freon and the compressor pumps 200 psi which is oem spec.

the ac stayed cold for 2 hours sitting in the garage. then after an hour of driving it gets really hot. it randomly turns on and off.