Hey guys, having an issue that now has me baffled. Rewind to Friday. I'm driving down the interstate, and my A/C started blowing warm air. I still had freon, so I jumped the high/low switch with a paper clip and the compressor immediately kicked on and it started blowing cold. So I bought and installed a Santech switch from Autozone, and had it recharged. Yes, we put it on a vacuum beforehand. We had it blowing at 46 degrees Friday night. I drove it 180 miles home and it worked perfectly. This morning, I drove it another 150 miles, and it crapped out in just about the same spot where it did Friday. I tried to use a jumper again to see if the switch had gone bad, but got nothing. Any thoughts?
Need an A/C guru
- Thread starter jsukey
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Starting to think that the compressor might have seized up. When I unplug the switch, the RPM's drop. When I try to jump the plug, the RPM's go back up. What are the odds that switch would go bad, and then the compressor shortly after? When the system was recharged, he put it on a vacuum pump for around 20-30 minutes. Could that have pulled the necessary oil out of the system and ruined the compressor? We never saw anything come out of the pump. We recharged it with 2 cans of straight R 134a.
TheDurk
Elite Member
You can't diagnose A/C without high and low pressure readings. Get a set of gauges or take it to someone who has one.
For all you know, you had a bad expansion valve or other blockage, system was cutting off due to HIGH pressure, you replaced a perfectly good switch, and now you are looking at the same thing again.
For all you know, you had a bad expansion valve or other blockage, system was cutting off due to HIGH pressure, you replaced a perfectly good switch, and now you are looking at the same thing again.
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LittleCaesar
New member
+1 on the expansion valve. Probably sticking. A new Denso is $30 or less. Get a Denso drier at the same time though, your system will like you.
And no, pulling the vacuum doesn't suck the oil out but burns up the water vapor in the system. The less H20 in a AC system the better it performs.
And no, pulling the vacuum doesn't suck the oil out but burns up the water vapor in the system. The less H20 in a AC system the better it performs.
LittleCaesar
New member
Not to rob the OP's thread nor Durk's sage advice but these from Harbor Freight work just fine for DIY use:
https://www.harborfreight.com/ac-r134a-manifold-gauge-set-60806.html
Two rules to follow to give them long life: never store in extreme heat or cold and relieve all the pressure in the lines after each use if not using them on a daily basis.
AC clutch? You can ohm out the electrical and see if it is getting power to eliminate the switch. With the engine off can you turn the compressor by hand? Does the compressor turn when the system is turned on? Change fuses and relays just in case. Just a few things to check remember the rule KISS keep it simple stupid. bought a starter the other day only to find out it was a loose wire. go over all the simple things first even if it doesnt seem like that is it.
Never know whether to call a mechanic or a Priest for AC problems.
Never know whether to call a mechanic or a Priest for AC problems.
Did you happen to move the HVAC control to heat and then back, each time it quit working?
If I use the heater I have to get under the hood and manually push the heater control valve cable in the closed direction - and it moves ever so slightly.
I haven't cared enough to see why that would cause the air to blow hot, but I know that is my problem. It may be yours as well.
If I use the heater I have to get under the hood and manually push the heater control valve cable in the closed direction - and it moves ever so slightly.
I haven't cared enough to see why that would cause the air to blow hot, but I know that is my problem. It may be yours as well.
TheDurk
Elite Member
You didn't rob much from me. Those are exactly the ones I have. Pros will diss them, I'm sure, but they work fine for me. My pump is HF, too, but I got the two-stage (on sale). I maintain six A/C vehicles, mostly older.
https://www.harborfreight.com/3-CFM-Two-Stage-Vacuum-Pump-61176.html
Good advice on storage of the gauges.
Here is my sniffer. Not cheap, but has more than paid for itself since I bought it in 2013. Beats the hell out of trying to use dyes. Dyes are useless to find an evaporator leak (what I currently have on the 4Runner).
https://smile.amazon.com/gp/product/B004HMKPMK/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
Honestly, I have had to do more study and research to do A/C work than any other skillset I have had to learn to work on modern cars. You can't half-ass this stuff, although the pros promote a lot of FUD to intimidate us DIYers. You don't need a $3000 flush and fill machine to do A/C work, but you do need to do your homework to get your oil and refrigerant levels in spec.
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FrenchToasty
New member
Like someone else said KISS
And to what the durk said, those switches are there to protect the system, bypassing them might have let the evap flood(possibly clogged cabin filter or evap frosting from low charge), sending liquid to the compressor which could have been tripping the hi pressure switch and then running it that way further damaging with less oil return. Also is it humid as all get out there? Evacuation is critical...........when it's humid or you have the system open for a period of time; TRIPPLE EVAC is a must!!!(evac, purge with dry nitro, evac....so on)
So you possibly either have moisture in your system clogging a orfice or the compressor has been compromised
I'm a low temp nerd, but hope something works out for you
Because the system was operating correctly and then stopped cooling, and did this at least twice, the compressor is working. So either power is being interrupted, shutting the compressor off, or some other part of the system like the expansion valve is failing. Is the hub of the compressor turning when the system is blowing hot air? If it is, that points towards the expansion valve. If the hub isn't engaged, that points to something electrical shutting off power to the compressor. When you hook up he gauges, if the low side goes to zero or into vacuum, the expansion valve is the problem.
19963.4lsr5
New member
I've taken apart two compressors that the reed valves were all broken and ended up in the inlet of the condenser.
I bought all my AC tools, but my gauge set, at swap meets over the years. Every leak I ever had was a EVAP. And I cry every time the sniffer goes off inside the vehicle.
Post back your gauge readings.
Sent from my iPhone using Tapatalk
I bought all my AC tools, but my gauge set, at swap meets over the years. Every leak I ever had was a EVAP. And I cry every time the sniffer goes off inside the vehicle.
Post back your gauge readings.
Sent from my iPhone using Tapatalk
Okay guys, time for an update. I've been at work all day, and couldn't put hands on the 4Runner. When I left work at 6, I started it up and was just curious to see if it would kick on. What do ya know...freezing cold air! That tells me that the expansion valve is intermittently hanging. I couldn't get in touch with my buddy, so I stopped by autozone to rent a set of gauges. Of course they were all out on loan. I will update with more info when I have a chance to put some gauges on it. Work is pretty busy right now. I'm certainly not looking forward to tearing out then entire evaporator to replace the valve and drier. Does anyone have any pointers to tearing it out?
JRZEE2000TR4LTD
Senior Member
You may just have a little moisture in the system which is icing/ restricting the expansion valve. Recover, evacuate overnight, and replace the drier. The drier is in the front of the truck next to the condensor. Try that before you tear into the dash for the expansion valve. Also, really need to know the Hi/low side pressures. Those will tell you if somethings going on with your expansion valve.
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