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Old 08-19-2009, 05:41 PM   #1
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Heat pump - Low light coming on

Hi all, it's hot outside!!!and the wife is beating me up cause I haven't had the system on so far this season. So just now I tried it and the compressor light for low pressure comes on two seconds after thermostat calls for cooling. Been a while since I used gauges and hoses. System is a 5.5 ton Hydrodelta geothermal heat pump about 10 years old. I would guess it could need some freon. I probably have a chart somewhere but if someone can direct me to a site or give me some direction on what a normal charge of R - 22 should be I would greatly appreciate it. Or if you are thinking I'm off base and it might be something else I would sure like to hear from you.



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Old 08-19-2009, 08:43 PM   #2
Join Date: Nov 2006
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Heat pump - Low light coming on

If the low pressure lockout comes on then it's trying to protect itself from running without refrigerant. (preventing bad things from happening).

If it's low on refrigerant after 10 yrs then it has a leak. You can get out all the charts, hoses, gauges, gas jugs but you also better get out the leak detector or history could repeat itself.

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Old 08-20-2009, 09:26 PM   #3
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Heat pump - Low light coming on

Hi hennyh, Thanks for the advise. I noticed that the hi-pressure valve was covered in a damp oily film. Didn't notice anything strange anywhere else. I hooked up the manifold and added some Freon. I then looked at as many joints as I could using some bubble solution. Only place I found to have a problem was at that valve. Tiny amount of bubbles formed and only thing I could think of was to put the manifold hose on and off a couple times and then put the cap on tight. I think I either "fixed" it or there is such a tiny amount of bubbles that I don't care. Now don't get me wrong, but I'm having trouble justifying the expense of calling in an HVAC tech and have them purge, fix and refill when I have a 30 pound tank with only the amount removed that I used today. Since I have the low side safety and we know it works I think I will take my chances with having to do this once every ten years or maybe a little sooner. The valve may well be the culprit it may have been leaking from day 1 or the last time I had it professionally looked at was about 4 years ago maybe when he put his manifold hoses on the valve didn't seat properly? If so I might have 4 years or maybe more. Regardless, I'll just watch and wait. What do the rest of you think?? I may need to work on it sooner, I want to move the water lines (geothermal) so if I do that I will need to call in someone to purge the water lines of any air so I could do it all at once.

thanks for the help. Could still use some advise on how much Freon I should put in.

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