Hey guys,

This weekend my AC has been acting crazy, First of all its been -20 Celcius all weekend. Right before the cold stream I had brought my car to a interior/exterior car wash because it was way to cold to attempt to clean the car myself. Problem is that they really used some shitty windex all over my windows that froze on the inside when I leave my car parked outside. Anyways I need the AC on for the defrost in full heat. Thing is when I set it to max heat with the defrost front and rear setting and hit the AC ON button nothing happens. I drive for about 10min then feel the AC compressor kick and then nothing for the next 15min. I set it on COLD and nothing again NO Compressor engagement.

I then left the car in an indoor heated garage and then hit AC on and then felt the compressor engage. Does our AC system have some sort of temp sensor that doesn't engage the AC in extreme cold or when not necessary??

I know if I was running low on freon the comp would not engage, but my pressure is fine the only problem is the intermittent engage in cold weather out. Could be a faulty pressure switch??

 

I think you are freaking out the system asking different things
dont set it to heat and defrost- just push the front defroster button,
that will engage AC to remove moisture- which is how they defrost

once thats good- switch to auto midrange temp and let it do its thing

 

clean windows with something right away!!!

 

It should work even when its that cold. How id the Freon level in your AC? has it recently been serviced? Its possible a connector got wet from the car wash causing it to not work?

 

Ok so I took it in today to an AC shop. Tested out everything freon is ok, no leaks. I noticed under 30F the Ac compressor does not engage. Anything above 32F and it WILL engage. If the car is left out under 30F and I hop in put the defrost on the AC doesnt engage only the heat from fan. My mechanic has never done work on the climate unit for the TL but told me he has seen alot of Honda's that has temp sensors in the system that doesn't let the AC comp work if the Fan ca reach the desired temp. I know it sounds weird, but I really don't know if I have a problem or if this is normal.

If I get into a heated garage the AC comp kicks as soon as I hit the AC ON, As soon as I exit and enter cold 30F and under nothing happens when I hit AC on!!

So far the freon is ok, Clutch works fine whats next??

 

Yes, it's correct. There is a temp sensor for the condenser core. It functions to shut off the AC compressor to prevent the condenser core from freezing up.

So if the ambient temp gets too cold, and the condenser core is about to get frozen up, the AC compressor will not engaged to protect the system.

 

Actually, the temp sensor is on the evaporator; it keeps the evaporator from freezing up. Condensers don't freeze up, they generate heat when the ac is on. What keeps the system from working below 32F is the pressure sensor located on the receiver drier. It opens the circuit when refrigerant pressure is below 28psi which translates to 32F with 134a.

 

I just started having this problem. My compressor doesn't engage anytime it's under 30. Last winter it seemed the compressor would kick in regardless of temperature. It's a bit annoying when defrosting windows since the heat isn't hot until the engine warms up and the compressor won't kick in to dehumidify the air.

I'm not too familiar with AC systems besides freon recharges. The only change since last winter is the thermoblok install/egr port clean. My freon levels are good. Is this normal behavior?
Where /What should I check?