I've been in the HVAC/R trade for 40 years and only came across oil logging of an evaporator one time and that was on a low temperature reach in box. Oil logging is usually caused by refrigerant velocity return problems. I have not had any problems for 30 years but will keep my eye open. Thanks
One thing I've gotten stock on is the suction pressures dropping to the point that the system shuts off. This happened after installing a new condenser. I was told by the customer that the previous tech went there and stated they needed a replacement so I gave them a quote and they went with it then experienced the above issue. I too thought it was a bad txv at the time. Not a heatpump either. I suggested replacing it but they thought the issue was the new condenser which it wasn't.
Was having an issue with my heat pump air conditioner after checking just about everything I figured I have a bad TXV valve I was unable to get the low suction line pressure where it needed to be. I thought it needed more Freon. I tried running the heat pump for 15 minutes and sure enough the suction line pressure was back to where it should be. What I don’t understand is this unit is about 10 years old and we definitely run the heat pump in the winter , Why do you think the TXV valve is acting up and why does running it backwards? Make it work again?
HVAC Tech Tips Just want to say thank you again I did do that and it worked for a couple days then I started having issues again. The unit was going off on high limit so I’m looking into perhaps changing out the TXV thank you so much
Hello Josh. I am very interested to try this because I have been experiencing issues all summer long. Could you explain a little more on what is happening when this condition occurs. Or is this just for the heat pump system? I have a trane r410a system. Ac and furnace. If I ran the furnace instead of AC, how would it revert everything in the A coil?
HVAC Tech Tips thank you so much Josh for getting back to me with your reply. It makes total sense. I do not have a heat pump but I have a problem that I’m trying to figure out. Trying to learn by watching such great channels like yours. My best diagnoses is that my system is somewhat overcharged and my TXV has a restriction. One technician that looked wanted to replace the whole condenser. But I am still hoping that it is not a compressor (scroll type) because it runs smoothly and on the hottest or humid days it actually works the best. Just occasionally trips on the high pressure switch during start up. But I put a small misting system they are usually all the condenser coil to lower the pressure down. As long as I keep an eye on it (put a few wireless cameras to monitor moisture removal and A coil temperature so that A coil does not over freeze) it runs pretty smoothly and cools the house pretty good. But the high side is still pretty high over 400 psi. Sub cooling is 45 and superheat is high 15 to 20. Suction pressure is not so bad, about 110 psi. I have an 11 years Trane 4t ( past 10y warranty) with the r410a. So on one video the teacher was saying that if the sub cooling is high and superheat is high it is most likely the system is overcharged and there is a orifice restriction. Anyways, I do not want to bother you with all these details but if you have a suggestion I would greatly appreciate it. I need to either fix it or make a decision on the replacement by spring. Best regards!
The suction seems low and with the very hig sub cooling, it sounds like a txv problem to me. You can also check your blower and capacitor to make sure it’s running at full speed. When the blower is not running correctly it will make pressures look just like that. But If it’s fine, it sounds like a txv problem.
HVAC Tech Tips thank you so much Josh again for the advice. Yes I will check the capacitor. I did not mention that one person at work ( I work with some nice HVAC guys who maintain air handler’s at our plant) suggested for me to try running the blower on the lower speed during the hot 90 deg. days. It seemed like with that it was removing more heat from A-coil. But I did not have a gauge to measure the high line pressure. I am hoping to either purchase a manual gauge or borrow one from work to do that. Have a great day!!
Josh. Very sorry to bug you with this. hBefore measuring the capacitor on the blower motor I was planning to discharge it. Some do not recommend shorting between the legs saying that it may damage it. And I do not have a discharge resistor handy. What do you normally do? Or should I be just careful wearing gloves while measuring it?
I worked for mine but only for one cycle… I let my heat run for 15 mins… than I set it up for AC… than it does turn ICY… the radiator is frozen in my blower but after a cycle only it is only the TXV that is freezing… it doesn’t access the radiator anymore…. Any other clue?! Thanks a lot!
