View Full Version : Anyone do HVAC?
04/29/2009, 06:32 AM
I hate dealing with large companies that just want to sell me a new unit.
I've got a dual heat pump system for the basement that neither compressor is kicking on - checked all the electrical components and all looks good - starting voltage is there. One unit shows a low pressure warning, so my thinking is that there's a safety shutoff if the pressure is low to keep the comp from coming on.
Tech said both compressors are shot (one was working BEFORE he and his apprentice came and now neither work) and it's $2800 for repair or $3600 for replacement. I think I'm being scammed.
I know what the parts cost - if it wasn't for the EPA and lack of specialized tools, I'd repair it myself. DIY hardcore. I'm not opposed to replacing the unit but I want someone I can trust to tell me that.
04/29/2009, 06:29 PM
It sounds like you have a leak in your line set somewhere that you lost all your freon and there is a low pressure switch that will shut your compresser off so you dont burn your compresser up. You also have a high pressure switch that will do the same thing. I dont know how old your unit is, but you can always have someone shoot dye in your system to see where your leak is. If your freon is that low your compressers wont kick on because of the pressure switch, and if it did kick on it would freeze up. If you i would try to shoot the dye in the system to see if there is an obvious leak.
04/30/2009, 05:28 AM
It's about 9 years old, so it's not new for sure.. Thanks, I'll try that. I can hear the capacitor firing, so the cutoff is either between the capacitor and compressor, or the compressor is locked.
Any thoughts of the 'hard start' capacitors? Even if it will get me another year or two, it would be worth it (wife's schooling will be paid for).
04/30/2009, 02:01 PM
Hard start capacitors are a good fix on an older unit, and yes it will help the capacitors to turn on your compressor. Your low pressure and high pressure switches are on your liquid, and suction line so it will feel the freon flowing through the pipes. Couple questions though:
1.Does the contacter kick in when your are calling for cooling, are you getting 24volts to the contactor.
2. Are you sure you hear the capacitor at all is the top blown up on it at all.
3. Can you hear your compresser turn on at all if so does it hum and then shut off.
4. Does your compresser get very very hot to the touch.
5. Did anyone put any gauges on it at all and can you tell me the readings he was getting, and do you know what day it was and about what temp at all.
Ok see if you can answer any of those questions at all. You can bypass the cutoff switches just to see if your compresser runs at all but i DO NOT recommend you leave it this way or you will ruin your compresser and your unit will probably just freeze up. To answer your question yes the "hard start" capacitor will help to give it a jolt, but let try to figure things out before you go that route.
05/01/2009, 05:48 AM
Answering what I can:
1. Unknown - will check this weekend
2. Capacitor seems fine, it had voltage across and neither appeared to be out of normal shape. We did not test the strength (found a link that talk about using the ohm test to charge it, then switch to voltage which should go to infinity - will do that this weekend)
3. No, the compressor does not turn on at all.
4. Didn't notice the compressor getting hot
5. They didn't put the numbers on the page, just said "the pressure was fine" (very suspect). I had them out in January when one of the units failed to heat, it was a warmish day in the 40s if I remember correctly.
Thanks for your help! I owe you a frag or two!
05/01/2009, 07:20 PM
closefriend of mine that does HVAC in hbg. John Campbell. 773-0589. Tell him Keith sent you. Ask him to come out and give you an estimate. If that number doesnt work, let me know, but Im 99% positive thats his number
05/01/2009, 07:23 PM
Hmmmm very interesting if they say the pressure is fine, then maybe you have a bad low pressure cutoff switch. As far as the contacter goes you should have two low voltage wires going to your contacter, turn your T-Stat to cooling and measure voltage to see if you are getting 24volts. If your capacitor is blown you will know it, the top of it will be bubbled out.
Try this for go out and push the contacter in just to see if it picks up your fan, and compresser if it does then you know your capacitor is "good" and that something else is wrong. If it does pick up then check for your 24 volts because i would bet that you do not have 24 volts going to your contacter then. Try that and report back and we will go from there.
05/26/2009, 08:53 AM
Havn't had time to work on it much lately, but the fan comes on and I hear the a click like it's trying to turn the compressor on but it doesn't start. It seems to wait about 30 seconds, then repeats this.
I'm going to check the valves, another HVAC forum suggested that one may be stuck open or closed.
Tank was 86F when I got back from the beach so it's becoming critical that I get this taken care of - looks like I'm safe until the weekend..
05/26/2009, 02:16 PM
Shut off your unit and OHM out your compressor, or if you had a megger you could meg it to be sure. Make sure you compressor is not grounding out if so then your windings are shot, and that means your compressor is no good. OHM it out and let me know if you want what your reading is on it. If it reads open thats not good.
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