Auto Air Conditioning Problems

BigJim

Our 2000 Nissan Altima air conditioner will work when it is cool outside but not when it is hot outside. It will start to cool every once in a while when it is hot but then it will kick off and won't come back on.

I have put 3/4 can of coolant in but that didn't seem to fix it at all. Anyone have any suggestions?

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Jim

gregzoll

Could be the compressor shot. If you put in 3/4 can of freon, how did you measure the system to see if it needed any? You are better to take it to a shop that specializes in auto a/c and have them look at it.

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BigJim

The bad thing is I went to AC school for autos back in the 60s but can't remember a thing about them now. I guess you are right, I can't find a thing on line about car AC.

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Jim

joecaption

I just Googled auto air conditioning trouble shooting and several thoushand sites came up, he's one.
http://freeautomechanic.com/airconditioning.html

BigJim

Absolutely amazing, I have been all over the place looking and you find all of these the first time. I am even on a couple of car repair forums and couldn't find anything there. Thanks Joe, I appreciate that.

I think I have found the problem already, the thermal control amplifier. I went and looked at the link you gave me and it was one of them pay for the answer deals so we kept looking and found another forum and it has all kinds of information. I appreciate your help, I will let you know how it turns out.

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Jim

Marty1Mc

If that isn't the issue, then make sure your condenser fan is working.

BigJim

Marty, I was just reading about that this morning, are the cooling fans for the radiator the same thing? I just did an intake gasket replacement a couple of months ago and noticed that the cooling fan seems to run more after we cut the engine off than it did before. I do know the fans don't kick in very often. How would I check to see if that is the problem?

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Jim

Billy_Bob

Auto A/C systems have safety valves for too low of pressure and too high of pressure. If not enough refrigerant or TOO MUCH refrigerant, it will not work.

Warmer means higher pressures. You need to consult a factory service manual and see what the pressures should be and measure with gauges. The pressures will be in a table which changes per outside air temperatures.

As for the fans, probably if you have two fans, one fan should come on right away when the A/C is switched on. Then a second fan would come on when the pressure on the high side reaches a certain point.

To learn how this *should* operate for your specific vehicle, consult a factory service manual set of books (4 usually to set) sold at the dealer or helminc.com for many vehicles.

For fans not working, I've seen some which are bad - you can't easily turn the fan blade with your hand - does not turn freely. Replace fan if that is the case. (They are not cheap!)

Also a fuse could be blown. And a hard to turn fan could be drawing too much amperage and causing the fuse to blow.

BigJim

I will check the fans tomorrow, thanks for the information, I appreciate it.

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Jim

Carkid0007

Fans could also be coolant temp sensor if they continue to run. I agree with checking the freon level Due to improper freon levels making it shut off. I'll check tomorrow in the fsm for a 2000 altima and see what the spec is.

ukrkoz

2000 vehicle is most likely low on freon/oil mix. It's age thing. That it works intermittently is maybe cuz freon pressure in the system is borderline. That it works better when it's cool outside is simply because cold air cools down condenser radiator faster.
You should have two fans. one for radiator and one for a/c. a/c fan should kick in every time compressor kicks in.
does compressor clutch engage? as in - does it click, and then center piece, hub of it start spinning? does it slip?
is a/c belt tight enough?

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Marty1Mc

Not all Nissan's work the way you would think. Mine doesn't have two electric fans, but a mechanical fan and an electric condenser fan. The condenser fan isn't triggered by system pressure like most other brands. It's triggered by engine temperature. I have no idea why Nissan designed it this way. But, that's the way it works. I recently put in a larger radiator for additional cooling and now the temp doesn't get high enough (I think it's at 217 deg the fan kicks on) to trigger the condenser fan. The result is the AC will get warm at idle. It also doesn't have a high pressure switch. Nissan has some very strange designs.

BigJim

I checked the fans and they both are running and shut off at the same time. Since I replaced the Thermo Control Amplifier, it works every time so far, but the temperature has cooled off here for now also. The real test will come in a few days when it gets hot again. I have looked but haven't found a sight bubble yet, if there is one on there where would it be.

The clutch is kicking in fine now and I replaced the belts when I replaced the intake gasket. Check out how much fun it is to replace that intake gasket.

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Jim

Marty1Mc

If you have one, it is on the high pressure line (the small diameter tubing). Follow that line from the compressor, condenser and to the firewall. It may be on the filter/dryer if you don't see it anywhere else.

BigJim

Thanks Marty, I appreciate that.

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Jim