AC Doesn't Stay Cold

[myk]

I have a 95 4Runner that I got a little over a year ago. It's a 3.0 with a Automatic transmision. (Most gutless car with the worst gas milage I have ever owned, but it goes anywhere and I love it) I live in Tucson, AZ and it gets a bit warm here in the summer. The problem I am having is when the engine is cool the AC will freeze you out, but when I drive it for 45 minutes or so, less if I have to make some stops and turn it off, it starts blowing out warm air. The engine temp gauge doesn't seem to move from the middle, but I know the engine needs to get pretty warm for a change to register on the gauge.
I thought I had the great solution, I did the Taurus electric fan mod last weekend, put in a brand new radiator and new 185 degree thermostat, and it seems like everything is working fine. I have the Hayden adjustable temp fan regulator, and the fan seems to come on when it should, and it stays running for a while after I shut it off, just like I wanted it to. I only have the low speed hooked up, cuz all the posts I read said that the high speed wasn't really needed. When I took it out for a prolonged spin, IT DOES THE SAME THING AS BEFORE, except the air doesn't stay cool as long, and it's not even that hot out. When it was 105 out, before the mod, I could drive on the highway for about an hour before the AC started warming up. Yesterday it was only 90 out, and it started heating up in 1/2 hour. It has nice new antifreeze that is full, the AC fan in front of the radiator comes on when I turn the AC on :headscratch: Don't have a clue what to look at next. I put in a can of refrigerant a while back and the AC works great for a while. Before the mod if I was parked for a while and opened the hood, the AC would work fine when I drove again, that's why I thought if I had the electric fan that stayed on for a while after I shut the engine off I would be golden. Not the case. Sorry for getting long winded, but I'm a bit frustrated.
Any help would be awesome,
Thanks,
Myk

[Good Times]

Some things to look into:

1. A/C needs refrigerant (could be leaking or just no good)
2. A/C compressor going bad?

Not sure other than I suspect it's something with the A/C and not anything else.

[BruceTS]

This is quite a simple fix...... your AC needs recharging

when your refrigerant is low the temperature drops below 32 degrees, you'll get very cold air for a short period of time, then your system freezes over. After that you get warm air since there is no flow through the coils....

[MTL_4runner]

I doubt it just needs charging, it probably has water in the AC system and needs to be evacuated, then recharged. The water vapor is freezing inside the system and blocking the orifice in the evaporator. You really need to take it into a shop, have them pull a vacuum for 1 hour to check for leaks, then if all looks good they should add fresh compressor oil (with a fluorescent dye added to make any future leaks clearly visible) and add the proper weight of refrigerant (since overcharging the AC system can be as bad or worse than undercharging). I don't suggest you do this yourself unless you have all the tools (vacuum pump, recovery tank, manifold gauges, etc.....not many DIY'ers do.) It's money well spent especially if you live out in AZ where AC is not optional and needs to work at peak performance for maxiumum comfort.

Here's some more reading on the subject for you:
http://www.ultimateyota.com/index.php?option=com_smf&Itemid=26&topic=1045.0

[BruceTS]

The only way water can get into the system is if there is no pressure..... I doubt there is any water in the system especially since he lives in AZ. 9 times out 10 systems freezing over is due to low refrigerant pressure.

BTW I have all the proper tools and have been working on AC systems for years. Hehe still have a 20 lb bottle of R-12 and R-22.....

[MTL_4runner]

I'm always happy to be wrong if another can of refrigerant from Walmart fixes it.....in all honesty it could be either scenario and a set of manifold gauges would show you exactly which problem you had. If it was the evaporator freezing, the low side would be too low and if it was the evaporator orifice freezing, it would show the high side being too low. I must say I'm curious to see what finally solves the problem. I would definately have it evacuated anyway to make sure you don't have any leaks which might cause this condition in the first place.

[bamachem]

This is quite a simple fix...... your AC needs recharging

when your refrigerant is low the temperature drops below 32 degrees, you'll get very cold air for a short period of time, then your system freezes over. After that you get warm air since there is no flow through the coils....


that sounds like what it would be to me. if it has leaked down a little over the last few years, then this will happen. however, the TRUE fix would be to have it evac'd and then leak checked and fix the leak before a recharge. the "quick and dirty" fix is a can of freon (R-12 on the old systems and R134a on the "newer" ones)

[myk]

Thanks for all the quick responses. I have some gauges I can throw on to see if it's low and add a can to see if that helps. Probably a good idea to have it evacuated and checked.
Thanks again,
Myk

[myk]

I checked the pressure today with 2 different gauges and they both read a little high, @35-40psi. It was working great today on an hour plus drive in the heat, but then I parked for 6 hours, drove it home at night when it was in the 70's, and it never got cold. I bought the rig on e-bay and had it shipped from chicago, so it has only spent the last year in the dry heat. Looks like I need to have it evacuated and recharged. Any ball park idea how much that should run?

[MTL_4runner]

I checked the pressure today with 2 different gauges and they both read a little high, @35-40psi. It was working great today on an hour plus drive in the heat, but then I parked for 6 hours, drove it home at night when it was in the 70's, and it never got cold. I bought the rig on e-bay and had it shipped from chicago, so it has only spent the last year in the dry heat. Looks like I need to have it evacuated and recharged. Any ball park idea how much that should run?


The low side pressure of 35-40 psi might be ok, but we really need the high side pressure also to do any real comparison and troubleshooting. It will probably run about $100-150 for the evac and recharge service depending on how much refrigerant you need to buy (ie how much it is to refill your system minus how much your system still has in it). The service is well worth doing though.

[BruceTS]

I'm confused, you need to test it while it's running and should have two reading, one for the low pressure and one for the high. If you checked the low pressure side while it's not running, it'll show a higher pressure reading.

[myk]

Sorry for the confusion. I only tested the low side while it was running with 2 different gauges, I don't have a nice set that tests both, only a 2 cheap ones that test the low side, so I checked with both of those in case my crap gauges were wrong.

[fustercluck]

How often does the compressor cycle on and off?

[myk]

Finally had a chance to check about the compressor, and that seems to be the problem. It is nice and cold when the compressor is running, but then it turns off all by itself and blows hot air. If I let the truck sit and cool off, the compressor works fine again. Any ideas?

[MTL_4runner]

Finally had a chance to check about the compressor, and that seems to be the problem. It is nice and cold when the compressor is running, but then it turns off all by itself and blows hot air. If I let the truck sit and cool off, the compressor works fine again. Any ideas?


Have you had a shop evacuate and recharge it yet?......that would be your first step.
No sense in troubleshooting before you've done that.

[Robinhood4x4]

This sounds like a problem I had, however I never did figure out if my compressor was cutting out or not. By the way, the compressor isn't supposed to run continuously.

There is a recall for some earlier 2nd gen 4runners because of a faulty expansion valve. My 93 was supposedly ok from the factory so I'd assume you're in the same boat. The symptom I had was the ac would blow cold for about 30 minutes and then quit. If I stopped the engine and started it up again, it would blow cold for another 5-10 minutes.

A shop diagnosed it for me and offered to evacuate the system and store the refrigerant for me over a weekend while I replaced the expansion valve. They also specifically cautioned me that I change out the evaporator if I opened up the system. I fixed that over a year ago and it's good as new.

FYI, per the FSM troubleshooting section:

If cool air is intermittent check:
Magnetic clutch slipping
Expansion valve faulty
Wiring connection faulty
Excessive moisture in the system
AC amplifier faulty