1995 Pathfinder A/C

[Lunartic]

A/C compressor is turning off at the hottest times. When i slow down or stop at a stop sign the compressor turns off and when I speed up again it is coming back on. When I park it and run the car parked with the A/C on high it does not cool when its there idling. When I get it going down the road again its like ice cubes coming out of the vents! Any ideas guys??? Some switch or something else?

 

Trying to beat the HEAT!!!

Much appreciated

Blair...

[max_stryker]

I had the blower motor fail on my 95...the heat AND a/c was intermittent...and when i hit bumps... fahgedaboudit.

 

Worth a look into it i THINK.

[vengeful]

That's normal. With the extreme temperatures across the nation recently, it's to be expected. The AC Compressor will shut off at low load to keep the engine from overheating. The ECU receives signal from temperature sensors, vehicle speed sensors, fans, etc to determine the air flow across the radiator/condensor. If the air flow is not enough to sufficiently cool the engine as well as the refrigerant, the ECU will turn off the compressor to prevent the engine from overheating and causing damage.

 

This is what's happening.

 

Also, if your fan clutch is bad, the AC compressor will shut off sooner/more often than if it were good.

[max_stryker]

Well if it turns out your compressor IS failing.

 

bryan on AC has one for sale.

[Lunartic]

Hi there again fellas. Its still doing the same thing so I think that the compressor may be pooched. When it idles the compressor turns off. When I start moving the truck the compressor kicks back on. I have checked all the wiring around the unit and inside the cab (thinking that something may be loose,) but still nothing. Is there some kind of pressure switch or something that may be failing when i stop???

 

DUNNO but trying to keep cool at stops or in rush hour is a BITCH!!!

 

 

Any answers or ideas would be appreciated... :confused:

 

 

 

:furious: HOT BLAIR.....

[vengeful]

More likely than not, it's your fan clutch that's pooched. If the AC cools properly while moving, then the compressor is fine.

 

What is happening is that there isn't enough air flowing over the AC Condensor and the Radiator to efficiently cool both of them. Thus the ECM turns off the AC Compressor to more efficiently cool the engine so it doesn't overheat and get damaged.

[Lunartic]

Hi man and thanks for the reply. So I may have a troubled fan clutch you think eh? How do I check it? It spins when the engine is cold and hot both ways with ease.

 

Blair...

[88pathoffroad]

When it's hot it should lock up. If it spins freely when hot it's toast.

[Precise1]

Does the compressor kick on when you increase rpm or move ?

 

Sounds like the fan clutch is tired. Spin it by hand when cold. If it rotates more than 1/4 to 1/2 turn may freewheeling, it's probably shot. When you start cold, can you hear the fan sound shange after 15-30 seconds ? If the fan clutch is bad you should notice the truck running hotter at low speeds.

 

B

[Lunartic]

Going to the wreckers tomorrow to get a new used one.

Thanks to all. I think I can get one for about 25 bucks.

[Lunartic]

Hi there guys. Nope not the fan clutch, I got a used one to try and the A/C is still shutting off at stops or in rush hour. When I speed up it comes back on!!! Is there some kind of pressure switch or something else that might possibly going wrong with this?

 

Bitcher its hot today!!! Have to stay :cool2:

Blair.....

[vengeful]

What are the temperatures like?

[John Boy]

Hi there guys. Nope not the fan clutch, I got a used one to try and the A/C is still shutting off at stops or in rush hour. When I speed up it comes back on!!! Is there some kind of pressure switch or something else that might possibly going wrong with this?

 

Bitcher its hot today!!! Have to stay :cool2:

Blair.....

Could be the low side pressure switch which kicks the compressor on and off.

[Extreme90path]

From my experiences with a/c at the mechanics shop, sounds like your low on R-12 or R-134. I don't know what year your pathy is so I can't exacally say which you have. But if it is R-134 you can pic up a can of refiller at Wal-mart or any autoparts, but if your running a R-12 system, that stuff is like drugs... extremely hard to get and very expensive... but more effective. DO NOT MIX THE Two of them. But if your running R-12, and you don't want to spend the money on the coolent, conversion may be in order, which you have to have a certified shop to do that, so that they can dispose of the system properly. All vehicals have run A/C have an auto shut off for the compresser when the refregerent is low, so that you don't burn up the compresser... so it is very likely that is the problem... and the reason it cools while the engine is running at a higher RPM is because there is just enough in the system to keep it from shutting off, but at a low rpm the compresser can't push what is left in the system fast enough to cool properly. I would recommend at least stopping at a ASE certified shop and have them at least check the low and high side of the A/C system... that is you best bet.

Edited July 26, 2006 by Extreme90path

[Lunartic]

It was doing this at the beginning of the summer and I thought it was down on r134. It was still cooling just not at stops or slow driving. My friend had a proper hose and we got the bottle from an auto shop. We emptied the can into the system with the A/C on high as instructed. It seemed to get a little cooler, but is still doing the same thing. This is why I'm wondering if a sensor or pressure switch is letting go. IT SEEMS TO WORK PRETTY GOOD IN THE EVENING WHEN ITS COOLER OUTSIDE!

[mws]

I think pert near everybody's on the right path here... There are pressure switches in the A/C refrigerant circuit to keep the thing from melting down or bursting hoses. If pressures get too high or too low, they will tell the compressor to shut down.

 

Inadequate air flow over the condenser will cause pressures to get too high as the refrigerant gets too hot. If you're sure you've eliminated that as a problem, then it's time to get the refrigerant level checked.

Not enough freon, or too much freon, will cause improper pressures. Take it to a good shop and get it checked out.

 

If it is an R-12 system, I advise you NOT to convert to R134a. R-134a is one of the worst refrigerants ever made. It sucks, and has a much lower heat content. If the system was not designed for 134, it will never, ever work as well or be as reliable as you'd like. A proper conversion costs $100's, and still can only be 85% as powerful as R-12. That's a fact of physics, and no amount of marketing hype will ever undo it.

 

Seriously, I sincerely advise that you suck it up and pay the price for the R-12. And make sure the system is perfectly sealed so you don't leak it out. And don't use non-brand name R-12. There is some very unpure stuff coming over the border from down south.... And it will not be good for the system.

[mws]

Not enough freon, or too much freon, will cause improper pressures. Take it to a good shop and get it checked out.

We were posting at the same time. Sorry!

 

Take note of this! If you put in too much, it is just as bad as too little. There is an optimal amount of refrigerant required, best measured using pressure gauges. Get it done.

[Lunartic]

Hi there MWS. I have been talking to 2 mechanics and they said that it could not be overcharged... Is this true? Im going to check out these temperature sensors and ambient sensor and see if theres a problem there. I have driven this truck on hotter days and have never had this intermittent A/C thingy happen. Im looking into the connections again.

[vengeful]

That is very NOT true. Using one of those cheap-ass Piece of Junk self-recharge kits from auto parts stores, it is extremely EASY to overpressurize the system.

 

That's what caused the failure of the AC compressor on 3 of my idiot friend's cars. Just bring it to an A/C shop and get the system tested. Most places will pressure check it for free.

[mws]

The Venge be correct....

 

Lesson to be learned: Many "mechanics" do not understand the basics of what you think they ought to be experts about....

 

On the positive side, you now know those two "mechanics" are unqualified to touch your A/C system! You need to find someone else.

 

And honestly, just get the pressure check done before you invest any more of your time chasing sensors. Based on your problem reports, I am 95% sure that will be the culprit.

 

Good luck!

[Lunartic]

Well enough of this. I'm going to make a date with an A/C expert then. I have to get to the bottom of this.

Thanks to all.

 

Blair...

[fordsho90]

keep us updated and gl

[John Boy]

I agree with veng about those freon in a can crap. Most of the time what happens with those is you introduce air into the system ( did you purge the hoses?) and then you can't get accurate pressure readings.

 

Technically you can't determine how much freon is in the system with pressure readings, the only way to accurately measure your freon is by evactuting, pulling a deep vacccum, testing for leaks and then add freon by measured weight.

Edited July 26, 2006 by John Boy

[Extreme90path]

very correct.

[Lunartic]

Got it done. It was a little high on the pressure so the guy evacuated the system and had it set up. Then when it was idling there for him about 8 min or so in the heat >>> it quit, the compressor that is. Thermostat was at 3/4 or so. He grabbed the fan with a rag with no problem he said the used fan clutch I get was also pooched, so I wentt back and got another used one today. And guess what? She's not shutting down anymore. Well for now that is. See the thermostat on the compressor was doing its job and shutting it down from the lack of the air flow. The fan clutches were free wheeling. But not now.

Thanks again fellas. NOW :cool2: ING WELL

 

Regards Blair.....