a/c problems

[mckrishes]

2001 Chevy s-10 with v6 engine.

Topic

[Matt]

If you don’t have a set of manifold gages, or any experience with A/C work, I would take it to a shop. HVAC work is not something that that average DIY’er can really do much with, I hate to say. If the pressure is too low, the compressor won’t operate, but I wouldn’t suggest just adding refrigerant, as it may be a waste of money if say the compressor is locked up or the clutch coil circuit is bad.

[beaker60]

Absolutely agree with Beefy on this one,,,100%,,,with the cost of 134A these days,,you don’t want to be wasting money just to find out you have other issues.Take it to a shop and let them diagnose your problems..you’ll be happier in the long run and you won’t suffer the frustration of trying to figure it out.

[EricTheCarGuy]

++++1 Many times AC work involves a LOT more than just adding refrigerant, it could be an electrical problem, a mechanical problem, or a problem with the AC system itself and considering the environmental concerns as well as running the risk of dama

[gaseousmercury]

If you are an avid DIYer that owns two or more cars I would say go for it and buy a manifold set and a vacuum pump. These two tools are indispensable when it comes to a/c work. For those starting out I would recommend a mastercool manifold gauge set and a FJC vacuum pump. You can get both for around 200 or less. I think your best bet would be amazon or mechanicstoolwarehouse.com. I got my manifold from mechanicstoolwarehouse.com years ago and it still works great. I would also recommend getting a refrigerant O-ring set (I got my latest on amazon for under $20) having it will save you a bundle of time.

There are tons of a/c forums and educational sites with tons of videos. You can definitely do the job yourself if you have the patience, time. and room. Cleanliness is a must with a/c work, all parts must be meticlously clean.

Again, I only reccommend you investing the money in tools if you’re going to end up using them again. I live on Long Island where A/C shops charge you $150 for just opening the hood let alone putting a set of gauges on the system. I recently replaced the compressors and overhauled the entire A/C sytems on my 99 civic and 2000 odyssey.

If you decide to venture and do this….I am here to help

good luck and let us know what you decide

[mckrishes]

thank you for the responses. I’ve been reading about a/c systems and watching many videos on the subject. I understand that these are delicate systems and require attention to detail. I know that damage can be done if diagnostics and repair are not done properly. Given the cost of a/c repair, I am going to attempt to diagnose and or repair this myself if possible and within my ability. One thing I have realized is that it is not wise just to put freon into the system and see if the compressor turns on. I know that if the required freon is in the system and more is put in, it could damage the system. I also understand that when the freon is low, the compressor may not turn on. And I know that the pressure can’t be checked properly if the compressor is not running. What I am trying to figure out is how to test if the compressor is bad. I have heard of some solutions:

1. Discharge the system and put the appropiate amount of freon and see if compressor comes on. (A good idea, but not a cost effective one in my opinion)

2. Jump the compressor using a wire from the battery. (Could this potentially damage the compressor?)

I could test the wires going to the compressor to see if there was adequate power. If power to the compressor is good, then I can think of two things. Either compressor is bad or system is low on freon and computer won’t allow compressor to kick on. I guess option 1 is something I could do, but is there any alternative?

Thanks for the advice.

[mckrishes]

I double checked the readings. This time at 70 degrees fharenheit ambient temperature. I got low side readings of 25 and High side reading of about 250. According to the chart it should be around 35 for the low side and 160 for the high. I am not sure if this is significant for a leak, contamination or if I need to evacuate the system completely and recharge appropiately.

[gaseousmercury]

With the vehicle off, unplug the compressor, then with a piece of wire jump the plug to the positive terminal of your battery. If you hear a click that means that the clutch on the compressor is engaging. If the clutch is engaging odds are it is a pressure related reason why the compressor is not engaging. I would also check the compressor fuses and relay. A set of manifold gauges would really be valuable hear. I would suggest buying a cheap set or see if your local parts store will rent you a set.

[mckrishes]

i didn’t have a long enough wire to connect from the battery to the compressor. so I unplugged the wire to the low pressure switch and I jumped the wire. When I did, the compressor kicked on and the clutch engaged. I figure two things. Either I don’t have enough freon in the system or I have a bad low pressure switch. Would checking continuity in the low pressure switch be a proper way to diagnose a working switch? I am not an electrical expert by any means. If continuity is good then my other option is to leave the wire jumped while I check the system for pressure. I know that running a compressor with low freon is not good, but what other alternative would I have? I could just place freon in the system, but then I would risk overcharging the system?

[mckrishes]

well im not sure that testing for continuity was appropiate in this case. i checked the switch it self and the wire and got no continuity. I already know the wire side is working because I jumped it and it worked.

[college man]

By jumping the LP switch you proved the circuit works. But without knowing how much charge is in
the system. you really can’t go much farther without a set of R-134A manifold gauges. don’t leave the
LP jumped. the compressor relies on refrigerant gas coming back to cool the compressor. you will
burn up the compressor if you run it jumped. Thats why the LP is there. to stop the system when
pressure is lowC8-)

[mckrishes]

O.k. So I bought a set of manifold guages. I attached them to the low side port and high side port. I jumped the compressor and got 0 psi for the low side and about 40-50 psi for the high side. I believed that this was due to the system being low on freon.

I added about one 16 ounce can of freon and the compressor started working again on its own. My ambient temperature was around 89 degress farenheit and according to the chart i should be at 45-55 psi on the low side and 250-270 psi on the high side. My readings are: low side = 45 psi and high side = 300 psi. I am not really sure if that high side pressure is something of concern or if that number is o.k since it is about the 270 mark. The system is cooling good now and I only used about a little over 12 ounces of freon.

[Matt]

A few things that come to mind. Since the system was almost totally empty, you have at least a small leak somewhere, and there is air in the system now, as well as moisture, since you didn’t draw the system down to add refrigerant. The fact that you have nothing on the low side and 45ish psi on the high side, as well as a higher than normal high side reading after you recharged the system could indicate that the metering device is clogged, possibly from debris from a failing compressor, as I imagine you didn’t add any oil. I’m glad you got the system to cool again, but I honestly think you just put a band-aid on it, and you will be in for a major repair in the near future.

[dreamer2355]

I would have the system professionally evacuated and held under a vacuum to check for leaks then repair and add freon as necessary.

[Matt]

Quoted From dreamer2355:

I would have the system professionally evacuated and held under a vacuum to check for leaks then repair and add freon as necessary.

Yes! Also, and I know this is nit-picking, but Freon was a brand name for R12, and there are other brands. That was Dupont’s brand name (I think). Freon is pretty much non-existent at this point, and isn’t being produced anymore. The correct term is R12 (old cars) or R134A (most current vehicles) for automotive applications, and R22 and R410 for most home/commercial HVAC applications. My old man is an industrial HVAC superstar, so I am probably just a bit OCD about the term, but it’s NOT freon.

[Matt]

Quoted From mckrishes:

I double checked the readings. This time at 70 degrees fharenheit ambient temperature. I got low side readings of 25 and High side reading of about 250. According to the chart it should be around 35 for the low side and 160 for the high. I am not sure if this is significant for a leak, contamination or if I need to evacuate the system completely and recharge appropiately.

Again, these readings suggest to me an overall low charge, and a clog at the metering device. The static pressure should mirror the ambient temp, i.e. 70 lbs both sides at 70 degrees ambient temp with the vehicle off.

[Author]

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