High side pressure cut off switch blew out the back.

[Hank]

The high side pressure cut off switch on my 8 month old compressor blew out the back of the unit.

In the shot below you can see the green oil in the circle being reflected in the mirror.

Question, what would cause it to blow out? Especially if it is supposed to be a cut off for high pressure?

[chevymaher]

Circlip wasn't installed correctly. Improperly seated and worked completely out. Then the switch just falls out over time.

[97cargocrawler]

I agree with CM. The whole unit looks like it popped out.





Good news is you should be able to just pop it back in and reseat the clip. Bad news is the system needs to be recharged and you don't know how much oil you may have lost.

[Hank]

Thanks guys.

Quick questions.

Once, with this compressor, I had warm air blowing in the driveway, right after startup. High side pressure was way up over 350. So I shut off the van, restarted it and pressures dropped to normal. In theory, the high side switch should have shut off the compressor right?

Would the system run if the high side switch was not plugged in? I haven't tested it with a meter yet. Wondering if they shop never plugged it back in or if just being the original switch it was bad or just the plastic got brittle and it blew out.

Yes, now I'm concerned about oil. I've only checked with a mirror but see some oily film blown onto the oil filler tube but do not see puddles. Should I pull the compressor, dump/measure the oil and re-fill? Or just suck and ounce or two up the lines when I fill?

The shop wants 100 plus 25 for the switch, I can get the switch on eBay for 9 shipped and 12 cans of R-134 for 49 shipped. Would like to sort this out on the cheap if I can.

[chevymaher]

Yes high side switch should have cut it off. It was defective. I never though about it working unplugged so that is a unknown to me.

You didn't loose enough oil to worry about. But if it makes you feel better they sell refrigerant with oil in it at the LAPS. Add a can of that. I wouldn't worry about it.

Yes just follow your plan put in the part and re-fill. you will be fine. I would replace the orifice valve. It is 20 bucks. There is a reason it was running such a high pressure it is probably blocked or partially blocked.

[Hank]

Thanks for bringing up the o-tube.

I bet it is clean as I had the system flushed twice before this compressor. I also replaced the dryer and o-tube, came with the compressor.

This unit has never got as cold at idle as the prior compressors. Only in the low 50's, prior units are in the 40's I'm wondering if they sent the wrong o-tube with the kit? I see listings on ebay for several different types, including a lot of cheap ones that are only for the cargo van without rear air. All seem to say "fixed"

Advanced auto has one that says automatic adjusting for climates less than 105 degrees. They also have a special one for 105 and higher.

I'm thinking, as pressures were always good, of replacing the o-tube for insurance and going with one of the units from Advanced. It is typically 80's -90's here in FL. Intake temps can be over 100. Think I'm save with the less than 105F in this case?

[Lumpy]

Thanks for bringing up the o-tube.

I bet it is clean as I had the system flushed twice before this compressor. I also replaced the dryer and o-tube, came with the compressor.

Still, it's the cheapest and easiest to install part you'll ever replace. And flushing the system doesn't clean the orifice. It's by definition a tiny space where stuff is asked to pass through. Collects everything. Mine was five bucks. Like a thermostat, it's cheap and simple to replace - eliminating one possible problem before it even becomes a problem.


Lump

[Hank]

You're right Lumpy.

I think I'm going to skip eBay on this and hit Advanced. Discovered the switches are color coded and they have an auto adjusting o-tube from Factory air. Sounds like it will solve my idle air temp problem.

http://shop.advanceautoparts.com/p/toug ... ifice+tube

[Hank]

And last quick question, just to make sure the shop did not flub the o-tube install.

Which way does it go? screen up or screen down.

[Lumpy]

There's usually an arrow on the side of the plastic. Direction of refrigerant flow. The bigger end goes up, smaller end (with the orifice) goes down.


Lump

[Hank]

Got the new switch and orifice tube in today. Old one was clean but they messed up the o-ring so that could have been some of my low rpm temp issues. Will post a pic later.

Held a vacuum so I charged it. It was 60 here and I was getting 38f temps from the vent and seeing some water freeze on the front evaporator line.

Here is where it gets odd. Once in a while, only at idle, I would see the high pressure side climb way up to 350-370. Checked the spec on the high cut off switch and it is 430. The low would stay close to 20-22.

Temps would climb a little to in the 40's. Sometimes it would fall on its own other times I tapped the throttle and it would fall. At idle I don't cycle, it never has.

Pondering that it could be a flaky low pressure cycle switch. What do you guys think? It is only 20 bucks to put a new one on and worth a test.

Also does the low side cycle switch have a shrader valve on it so I can safely remove without blowing out all that new freon? Read a post somewhere that the 05 suburban does..

Thanks

[chevymaher]

No the low pressure switch being gone will drain the system. Mine only cycles when I am driving at idle it never does.

[Lumpy]

I might be too late -

Those auto adjusting orifice tubes.

A friend of mine, mechanic for the city - works on police cars, city owned trucks and cars etc, said those auto orifice tubes are poo. They're made for temperature extremes like Phoenix. But they don't work for him in hundreds of cars in phoenix. I tried one anyway. Sure enough, it goofed with the hi side pressure all over the place. I went back to the 5 dollar fixed orifice tube.


Lump

[Hank]

The tube came in two flavors, > 105F and < 105F. I got the <105F as I'm in Southwest Florida.

I saw the funky high pressure readings with the old orifice tube as well. Below is how the old otube came out.

I'll know more about the idle temps when it hits the 80's down here next week. Have to wait for this 50F "cold front" to pass. I'm hoping the old otube had a little bit of blow by as that could explain the warmer temps at idle.

If anyone has any thoughts on the intermittent runaway high pressure, I'd appreciate it.

[Lumpy]

... Below is how the old otube came out.

That looks really clean from what I can see in the pic. You must have a clean system. No gunk floating around.


Lump

[Hank]

Wanted to post back here.

I see a difference with that variable o-tube. It is able to keep the van cool at idle when it's 93+ and the wife is sitting in car line.

The only funny thing is it makes noises at times. At power off, start up and major RPM changes. It takes a minute or two to stabilize when you first start up and drive the van. I get some less cool air and some noise then the noise stops and cold air comes out. Pressures are good.

Just wanted to post back an FYI

[Lumpy]

Glad to hear that variable O tube is working for someone, Hank.


Lump