No A/C with defroster

[charbaby]

'04 Nissan Altima 2.5S

About a week ago in the evening, I noticed that my front windshield(inside) did not defrost/clear up as quickly as I thought it should. Not a real big deal as I wasn't in a big hurry. I didn't pay too much attention to the defroster after it had finaly cleared the windshield.

Jump ahead! Now, what I am noticing is that, when I turn the HVAC control over to defrost and turn on the fan, I am not feeling the AC clutch kick on. Not that it was all that noticable before but, if one would pay attention to it, you'll notice/feel the AC clutch kick in.

The AC had worked fine all summer without issue and I even recently used the AC on a very warm mid OCTOBER day to cool off the interior of the car. Now it's too cold outside to tell if the AC is working(temp control on COLD/fan on high) or if it's just the outside cold air as it is now in the 30's/40's deg F.

The other day, I have tried the HVAC on several occasions after starting the car. I don't feel/hear the AC coming on! The defrost works OK but, I think I may have either an AC leak or a bad compressor.

I checked my '01 Lexus RX and hers works fine as it should, engine running of course as nothing will happen until the engine is running. I'll check my daughters Mazda3 when she comes home for the holidays.

Any thoughts or tips would be great!
Any other questions you may want to ask?
What to look for and try?

Thanks in advance,
CB

 

[charbaby]

And yes, I can live without the AC during the upcoming winter but, I do like the way the defroster works with proper operating AC and to help dehumidify the glass inside the car. So if there is an issue, I'll get it fixed in the Spring.

 

[Milkman]

Get someone to operate the HVAC controls while you are under the hood. That way you should be able to hear/see if the AC compressor is cycling on. Are you getting good heat out of the vents ? Are your carpets dry ? Are any of the other windows fogged up ?

 

[jorton]

Originally Posted By: Char Baby


The AC had worked fine all summer without issue and I even recently used the AC on a very warm mid OCTOBER day to cool off the interior of the car. Now it's too cold outside to tell if the AC is working(temp control on COLD/fan on high) or if it's just the outside cold air as it is now in the 30's/40's deg F.



Thanks in advance,
CB


Sounds like the refrigerant charge is ok.

 

[HerrStig]

Cars today have computer controls for the compressor. They don't want the evaporator getting so cold that frost forms on
it on a cool damp day. I suggest putting the vent on "recirculation" and the heat full up (if you have "manual" AC control) -- once the interior gets warm the compressor clutch ought to engage. If you have "automatic" climate control things are more complicated, but there are OBDII "check engine" codes for the AC system.

 

[Virtuoso]

Some car's will not engage the clutch if the outside temperature is too cold. Our van stops engagement around 35 degrees or so.

 

[UNC036]

i suspect a low refrigerant level or inop low pressure switch.

 

[charbaby]

Originally Posted By: Milkman
Get someone to operate the HVAC controls while you are under the hood. That way you should be able to hear/see if the AC compressor is cycling on. Are you getting good heat out of the vents ? Are your carpets dry ? Are any of the other windows fogged up ?


Yes, carpets are dry and the heat is good. You'd never know anything is wrong(if there is even anything wrong at all). I may be concerned for nothing.

Originally Posted By: HerrStig
Cars today have computer controls for the compressor. They don't want the evaporator getting so cold that frost forms on
it on a cool damp day. I suggest putting the vent on "recirculation" and the heat full up (if you have "manual" AC control) -- once the interior gets warm the compressor clutch ought to engage. If you have "automatic" climate control things are more complicated, but there are OBDII "check engine" codes for the AC system.


The car has standard HVAC controls(no auto climate control) and even though it has been colder here as I mentioned above(>30's deg F), the engine often been running for better than 30 min and there is good heat. But still when I try the AC or defroster or what ever I need to do to get the AC to come on, I still don't here/feel the compressor kick in!

Originally Posted By: Virtuoso
Some car's will not engage the clutch if the outside temperature is too cold. Our van stops engagement around 35 degrees or so.


This could all be nothing and I am just realizing this now after almost 8 years of ownership. I could have sworn it was different and never noticed it!

Originally Posted By: AstroTurf
i suspect a low refrigerant level or inop low pressure switch.


Thank you and you may be right. Good piece of info!

Thanks all

CB

 

[mechtech2]

Refrigerant [r134a] loses pressure in the cold. And it is enough to not activate the low pressure switch. Somewhere around 40 lbs rest pressure.
So at 35 deg F or below, many systems should NOT activate the clutch.

 

[SHOZ]

Check the fuse for the AC clutch.

 

[Rand]

some cars wont run it below 40f or so.

there is very little moisture in the air at 40f so when you heat it to 90+F its a low humidity and you dont need A/C for defrosting.

 

[hypervish]

My car won't run the A/C below 32 degree F.

 

[charbaby]

Well, appearantly everything is working correctly.
I checked under the hood with a helper as "MILKMAN" suggested and the clutch is operating/cycling on/off. But as it was 29* deg F yesterday, the system only cycles as needed and appearantly this is something that I was not hearing/feeling.

I did check my daughters car(Mazda3) as I said that I would earlier. And hers work very similar to mine. Also as I mentioned earlier that, I checked my wifes Lexus and hers works more noticably and longer but too, the Lex is "auto climate control" and infact does work a bit differently.

The systems are all quiet(barely perceptible) in all of the vehicles in our household so, noticing them cycling on/off, one needs to pay close attention.

Thank you all for your comments and suggestions & Happy Holiday to everyone.

CB

 

[mechtech2]

Ambient heat from the engine compartment will heat things up so the AC may work in cold conditions after running the engine/driving a while.

 

[KrisZ]

Originally Posted By: mechtech2
Ambient heat from the engine compartment will heat things up so the AC may work in cold conditions after running the engine/driving a while.


Yes. I notice my AC kicking in even when it's -10C outside or colder, but that usually happens towards the end of my commute, when everything is warmed up.