****AC/HEAT Problem ALWAYS HOT AIR****

[AARONHL]

UPDATE TO POST #28

Thought I would get more publicity in this forum as well, but I have a 2004 6MT Sedan with an annoying problem.

This just started happening recently. I've tried all combination of modes, A/C on, off, recirculating, no matter what the temperature is set at hot air will flow through the vents. If I set it to 60*F, the air will cool down but it will not get chilly. Any temperature above (61*F+) hot air will fill the cabin and I will have to open the windows after about 30 seconds. This happens in AUTO and MANUAL mode. Once I turn it up to 61*F the air becomes slow and warmer.

With the A/C on and the temperature set at 69*F, the air is as warm as like 85*F. Regular outside air flow is WARM at a cool temperature (no A/C). After about 3 minutes you will be sweating at basically any temperature. I can't imagine how this would be in the Summer.

Cold air at 60*F, working normally.
Hot air at 61*, which is not normal.

I am 100% sure there is something wrong with my HVAC. I was just in my friend's Lexus, with Auto Climate Control, and at 70*F cold air was blowing from the top vents.

At 70*F (with the A/C on) in my G35, the air is hot! It smells like hot air does. Cold air and hot air have two different, distinct smells.

I noticed this problem a couple months ago. I'm a perfectionist when it comes to my cars, so I know what should or shouldn't be working on my G.

Both connections on the in-vehicle sensor are connected. I have also caulked around the engine bay to help, but I know that is not the cause because the air just started doing this within the past week. The problem still happens with a another in-cabin sensor.

Edit 12/13/2008: Even with a different HVAC control board and CD player the problem still exists!!!!!!!! I replaced the whole center console unit and still have no cold air above 60*F.

I don't know what it could be!!!! Anyone have any ideas?

Thanks,
Aaron

[AARONHL]

Bump!!!!

[gary c]

Hmm, always hot air sounds like Obamas choice for a vice president.... Oh I'm sorry, you ment your car....have your air conditioner serviced. Sounds like you have a leak in the system.
Gary

[AARONHL]

Joe Biden is the man! I don't know what you are talking about????!!!!!!

I will be looking into the A/C system. Any particular points to check? I have run out of ideas so I might just bring it to the dealer with a tub of KY.

[elrooko]

My family used to own an air conditioning and refridgeration business - my summer job was fixing air conditioners in cars every summer till I was 19.

Sounds like you have a leak but it also may be the compressor. First thing to check, turn your A/C on full blast - full fan and full cool and look under the hood to see if the A/C compressor kicks in. If not, it maybe a bad compressor, or all the freon has leaked out. If it was a leak, most likely it would have gotten progessively worse over the last little while. It if it all of a sudden just stopped working then either

a) your compressor is faulty or the wiring is disconnected and the compressor isn't getting power.
b) you have a large leak in the system somewhere and all the gas escaped at once,
c) there is a blockage somewhere - this is tough to diagnose, you will have to bring it in to check.

If the compressor starts but you still have no cold air then you have small leak somewhere. Check all the fittings and look for any that have a lot of oil and dirt around them. Air conditioning freon actually have oil in it to lubricate the compressor, if it escapes the oil seeps out onto what ever surface is causing the leak and dirt will accumulate almost immediately.

You should be able to tell if it is a major leak simply by finding a large oily spot. Most likely it is either the small high pressure hose that is near the air intake bracket down by the front of the car. Look for a narrow silver tube running the length of the car on the drivers side under the hood. If this looks good then a rock may have gone through your condensor coil (smaller looking radiator thingy in the front of the car). Look for a big wet spot on the front of that.

In any case, bring it into the dealer once you take a look at it and have a decent idea of what it maybe.

Good luck

[AARONHL]

Thanks for the thorough response! I am going to run those tests.

Keep in mind the air is cold at 60*F, but once I change it to 61*F the air is warm (even if the A/C button is illuminated).

For example, if I have the air on (without the A/C) at around 70* the air blowing out is warm. It is significantly hotter than air should be at 70*. Even with the A/C off, would the regular air circulation be effected so it is warm at a cool temperature setting?

I also noticed that the driver's side vent closest to the window is always blowing hot air (not at 60*F though) even with the setting pointed only at the feet. No other top/face vent blows hot air when pointed at the feet.

Thanks for the help guys!

[elrooko]

At 60 deg are you sure it is cold air and not just outside air? What happens is that the thermostat essentially just blows outside air at you when it is set to 60 deg. At 61, there is some heat that comes through. First thing to do is check the compressor. If the compressor is running when the AC is on, then at least you know that's working. If it isn't then there is your problem.

If it is running and you really are getting AC'd air at 60 and not at 61, then it sounds like a faulty AC controller or a bad thermostat. Never have heard of that before on a G so I doubt it is the problem, but not out of the realm of possibility.

The small triangle vent is a defog vent, it usually blows warm air at the window so when then defog is on so that may be normal. When the car is running and the AC is on, does the small silver tube that I talked about start to sweat and get moisture on it? You should also notice a puddle of water under the car when it has been running on a really humid day. If so then your AC is actually working as it should.

First thing to do is check the compressor, then look for wet spots (sounds bad, already laughed and smirked myself).

[dave]

You could try the suggestions in this thread.

[NismoG35S]

maybe it is the in-cabin sensor's harness? see if you can find the pin# on the hvac board and test for continuity or an open in 1 of the 2 wires. i would say run the ac if the lines in the engine bay get cold and hot then its not a leak/ac prob. i dont think its anything overly complicated either way, using consult you could check for a lot of hvac issues i say jus bring it in they can fix it quick and prob not cost you that much compared to the headaches of finding the problem yourself gl

[AARONHL]

How can I check to see if the compressor is working on the G?

The small triangle vent is a defog vent, it usually blows warm air at the window so when then defog is on so that may be normal.

I know that is, I'm talking about the actual heater/air vent always blowing faint hot air even if the selection is only at the feet.

The silver pipe with a couple fittings on it next to the air intake piping gets cold, but moisture is not building up on it.

[Blackmouf]

Have you installed a z-tube or aftermarket exhaust. Improper installations can result in the intake hardware rubbing a hole in the A/C line.

Edit: I'm sorry I re-read your post and it said you did experience cold air only at 60. I'm not sure I can help you with that one......

[Hyphy]

Cold air at 60 but get's warmer at 61...No idea.

I would take it to the dealer.

[AARONHL]

Why would the air still be hot at 65* without the A/C on?

[Kris79]

1. Most common.....you didn't completely or properly reconnect the AC adapter when you reconnected the HVAC unit. The AC plug is pretty picky on how it is connected. Disconnect the AC plug, taking careful account of the 2 little fragile retaining clips on the plug harness. Then, reconnect the 2 harnesses solidly and insert the 2 little retaining clips.

2. Less common....when you dropped (if you did) the panel under the steering wheel to get access to the driver side panel that borders the HVAC unit, you dislodged the in-cabin temp sensor. The temp sensor is that little vent grill that is near your right knee when you sit in the driver's seat. Check the white (or is it yellow?) harness behind the panel to see if that got loose somehow. When and if you dropped that panel, the wire harness there becomes very tight and could jar loose.

[AARONHL]

At 60*F full blast A/C, the inside cabin is cold and the line marked "L" is sweaty. I let it run for a couple minutes at 61*F with full blast A/C. The inside gets way to warm for 61*F and the "L" pipe is still sweaty.

I'm going to check the thermostat, but the temperature gauge is functioning properly.

Another observation is that I don't get a water puddle under my car anymore.