My a/c works great and blows cold in the morning on the way to work after my 03 Coupe has been sitting in the garage overnight. The problem is when I'm leaving work after the car has been sitting in the parking lot for 9 hours. In Houston the temps have been right around 100 degrees the past week or so.

Wasn't sure if it had anything to do with it as I'm not an a/c pro but I checked the coolant and it's at the normal level. When the engine is warm and Im sweating profusely I start the a/c at around 63 degrees and I can hear the fans kick in for about 5 seconds and then cuts off and blows the hot humid air from outside.

Again, I'm not sure if its related at all but I recently had the radiator repaired due to a crack in the head but the a/c was an issue before that. Would it be the fan, freon, compressor (please say its not the compressor)? Just assuming it couldn't be anything major as it works absolutely perfect in the morning under normal temps but just does not want to work in the ridiculous Texas heat.

Any help is appreciated!

 

Do you have the HVAC unit set to recirculate when you have the A/C on? I have a few different vehicles and I'm not sure if my G automatically switches to recirculate when you put on the A/C... .but in other vehicles that I have, the A/C is almost 2-3 times as efficient when you have it on recirculate vs vent, because you're cooling the already cool cabin air rather than constantly trying to pull in hot air from the outside and cool that down.

 

first bring it in to Nissan for a evac and recharge if that solves the issue you know you were low on refrigerant. If that doesn't fix it it could mean your A/C fan is outta whack. Does the car overheat when you are idle during the 100 degree weather?

 

Does your ac blow cooler when your driving on the freeway compared to idle?

 

Yes I generally keep the a/c on recirculate to avoid bringing the hot air from outside into the cabin.

I called a local a/c shop to let them know that I'd like an evacuation and recharge and they proceeded to tell me they've never heard of an evac and recharge fixing an a/c issue. I was like ok thanks. My main concern is being told that I need to replace or fix something that doesn't need replacing or fixing.

It did this at first when the temps outside were not as hot. Now I can hear the fan turn on for a few seconds and then cut out. Now it's just warm humid air even when on the freeway.

I'm assuming this is because of the heat because as I said previously it only does this when it has been sitting in the heat for an extended period of time. It works like a brand new a/c unit with ice cold air in the morning when it's not baking in the sun.

 

Any chance you have air in your coolant?

 

Would air in the coolant cause the fan to cut off after a few seconds? I haven't not tried to burp the car after I repaired my radiator. I'm curious if an evac and recharge clear everything out. What's the price range of that service?

 

if the air is cooler when your driving freeway speeds there could be a crack in your condensor or the fan relay is shorting and not staying on as long as it should.

Check your freon level, i would just recharger it since its cheap and replace your fan relay. If there's a crack in your condensor then thats going to be a lot of dinero.

I would do the freon and fan relay first since there relatively cheap, if not you can do a leak down test. See if there's a leak in the system. Your mechanic could've accidentally damaged the condensor while installing the radiator.

 

The motor's coolant should have nothing at all to do with the air conditioning system. They are completely separate systems. The engine coolant does impact your cars heat though, since it runs the hot coolant through the heater core to transfer heat into the cabin.

 

I wasn't sure- I has air in mine and for some reason it was causing my ac to blow warm air intermittently. I've actually read elsewhere that it's a cause... And having it burped fixed it... But hey- if that's just a coincidence then my bad.

 

Having air pockets in your coolant can cause your motor to run really hot... it may have just been all that extra engine heat waffing into the cabin.

 

I will start with the evac and recharge and see if that helps. The a/c was blowing great last night, like better than it's ever worked in the 3 or years Ive owned it. The fan stayed on while it blew very cold and the outside temp was around 90 degrees.

I'll check and come back with an update. Appreciate everyones input!

 

Check to make sure the auxillary fan is running when its hot out. If not then its the fan motor, sensor, or relay.

 

Took it to a shop up the road for an evacuation and recharge and it turns out I was low on refrigerant, a 1/2 pound to be exact. I believe he said the car holds around 1.25 pounds so 1/2 a pound was a considerable amount. The whole process took maybe an hour at most and I'm getting some cool air now. I'm going to see how the system acts on Monday after work when the car is sitting under the heat in a parking lot. I'm glad this was a relatively cheap fix compared to spending in the hundreds for a new compressor, fan, etc.

 

Please let us know if that solves the problem. I have an 03 sedan doing the.exact same thing. Topple mine to my local nissan guy who does all my work and he was perplexed. Thanks again, its too hot for this. This may make.me get.that m37s sooner than I planned .... Haha t