A/C problems

[DTro]

'03 Toyota 4Runner

I noticed the past couple of years that my AC hasn't been working as well as it should so the other day I bought a can of coolant w/pressure gauge.

I tried to follow the directions, and ended up putting the full 16oz in the system, but during the process I noticed that the compressor kicks on and off constantly about every 10 seconds or so. The pressure on the gauge would rise to about 55psi then the compressor would shut off and the pressure would drop to about 25psi at which point the compressor would kick on until the pressure built again and then shut off again.

Driving around today I noticed periods of which the cold air was working fine, then no cold air at all.

Any thoughts on this one?

[jmd1]

sounds like it is still low to me. not sure what the spec is for the amount but if it was way low it might hold 2.5 lbs or more.

[JOHNBIGDOG]

Just to clarify it is not coolant, which goes in the radiator, it is refrigerant.

You probably have a small leak leading to the loss of your refrigerant, causing the loss of heat removal "cooling." Get the leak fixed and the system will be good to go. Some where under the hood there is a label that tells one how much refrigerant should be in the system. usually over 1 lb.

I would recommend one brings it in to a specialist to be diagnosed correctly; so that you are not wasting money on refrigerant that will leak out.

[Jeremy airjer W]

The pressure on the gauge would rise to about 55psi then the compressor would shut off and the pressure would drop to about 25psi at which point the compressor would kick on until the pressure built again and then shut off again.

I hope you have this backwards. When the compressor is on the pressure on the low side should drop. With the compressor off the low side pressure should rise.

[Scott K]

Sounds like it is still low, add another half can and see if at idle the compressor starts cycling less frequently. It should stay running most of the time, then kick off for a couple seconds, then kick back on.

[DTro]

Thanks

Its really hard to get a pressure reading with it jumping back and forth I was a little hesitant to put too much in.

[delcecchi]

Isn't there something that can be jumped to get the compressor to stay on? Or am I showing my age and lack of knowledge?

[rundrave]

before you go any further, I must point out and ask if you have changed your cabin air filter? They can get dirty/clogged etc and definitely play a role inhow efficient your AC works.

Mine have gotten pretty dirty in the past when I don't change them when suggested.

[DTro]

totally forgot about that thanks. it has never been replaced and I will try that tonight

[MNice]

Isn't it obvious?? You need a AIS sticker in your truck.

Air-conditioning Information Sticker

[DTro]

Well it sure was dirty, but its still cycling from cool to cold. Maybe ill throw another can in there and see what happens...

[Jeremy airjer W]

If you can find a recharge with die I would dump that in. If it goes low again before the summer is over you can check for leaks with a die light and figure out what the problem is before adding more refrigerant.

[rundrave]

yeah that cabin filter was well over do for a change. Do you service your 4runner yourself?

Most of the time when I get any of my 3 Toyota's serviced at the stealership they always try to upsell me on one of those and I always pass until they show me when they look like yours lol.

[Eric Wettschreck]

At work today I had to replace a compressor on a big arse roof top AC, and was thinking aboot Dtros car. I have the vacuum pump hooked up to it and drawing vac so I have some time.

Somethings not adding up, here.

Darren, do you know if your compressor was cycling on/off prior to adding refrigerant? The reason I ask is if were low on refrigerant, the compressor would run and run and run and not shut off because it wasn't meeting head pressure. Or, it would run a lot, off a little, on a lot, off a little.

It's very possible your cabin filter was the culprit from the begining. Now that more refrigerant is in the system, the compressor only needs to run a very short time to meet head, then it shuts off. The only real way to know is to hook up a set of gauges. You need to know what the head pressure is to really troubleshoot this. If it is actually in an overcharge situation DO NOT jump a pressure switch to keep the compressor running, this could be bad. An overcharge will make it not real cold, also.

If you ever get my way or if I get your way I'll hook up a set.

[Eric Wettschreck]

Another quick thing you can check is, while running, ac on, put your hand on an uninsulated chunk of the compressor suction piping (larger diameter). It should be cold or at least cool and even sweaty. Put your hand on the head/high side/discharge piping (smaller diameter), it should be warm or maybe even hot.

If this isn't happening there's a problem with the ac system and we'll have to dig a bit deeper.

[Scott K]

Eric, car a/c systems have a low pressure cut off switch, so when the pressure drops below 28-30 psi, the compressor shuts off. This way it wont burn up the compressor when it is low on freeon.

[Eric Wettschreck]

Ah, I did not know that.

Feeling the suction piping will tell a lot, besides slapping on a set of gauges. If the suction piping isn't cold, it's prolly low on 134.

[DTro]

The drive home today will be a good indicator of how well things are working without a clogged filter. Thanks for the suggestions.

[DTro]

Well I'll be darned, it stayed cold the entire 15 miles home so I hooked up the pressure gauge and it read a stable 35psi.

Now I suppose I should put a new cabin filter in.

[rundrave]

well glad to hear it was something simple!