Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Condenser change

Swapped out old Coleman condenser with new Goodman. The IDC is a year old Mortex and my supplier matched the unit for me. After the changeout(did line flush, triple evac., and pulled vacuum to 500 microns on last nitrogen flush) the head pressure shot up to over 400 psi for about a 1-2 minutes. Started to trip breaker and investigate but pressure suddenly dropped to normal. The charge is r22 weighed in with new liquid line dryer installed. Unit continues to run good pressures, amp draw is normal. Never seen this before in my 6 years of this business. Anyone care to speculate just in case I were to have problems with this unit down the road!


  • Some more information

    What was the ambient temperature when you put the system into operation?

    What type of metering device is on the system?
  • Flounder1310
    Flounder1310 Member Posts: 14
    More info

    The ambient was 62f and uses a piston metering device
  • Ironman
    Ironman Member Posts: 6,366
    A/C or Heat Pump?

    I'm assuming a heat pump since it's still Febuary. Also assuming that you were in the heating mode. Assumining your charge is correct. Now, that's a lot of assumption, but you've omitted all this info and we have to start somewhere.

    If the assumptions are correct, then I would look at two areas:

    1. Your indoor air flow. Is it correct? Is this a VS AHU where the motor ramps up to speed? Is the coil clean? All dampers and registers open? Is there a zoning system?

    2. Refrigerant problem. Are you sure your charge is correct. If you have a mis-matched coil, then weighing in the charge will not assure its correct. You must check the super heat and I would be looking at discharge super heat particularly since suction super heat can be as low as 1-2* on some heat pumps in the heating mode. You must confirm you have the correct air flow before doing this or you won't get a correct reading.

    You may also have some debris that was in the piston that dislodged itself as the pressure increased.

    62* in the heating mode is nearing the upper limit of the heat pumps design range and head pressure problems woul be more likely to show up there than at low temps - especially if something else is not quite right in the system.

    With a mis-matched heat pump system, you may need to install a TXV on the indoor coil and charge the unit in the heating mode using the discharge super heat method I mentioned above. The TXV will help compensate for the imbalanced charge in cooling, but the system will never perform to its ratings.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Flounder1310
    Flounder1310 Member Posts: 14
    More info

    This unit is a HP. After the1-2 minutes that the head pressure rose and then suddenly dropped( to proper range according to mfg. chart info) the unit has run well, performing as it should in heat and ac mode pressures were not bouncing around. It was a very quick incident 1-2 minutes max. I was so concerned with the head pressure I am not sure what suction pressure did for the 2 minute span of time. I was thinking maybe the RV was stuck and switched or unstuck when pressure rose. I apologize for not including more info to begin with. Was just a little concerned because I have not seen this before. Anyway unit is doing a great job for my customer and wondering if anyone may have seen this before and if so did the culprit rear his head later!
  • unclejohn
    unclejohn Member Posts: 1,718
    Some thing

    Was probably stuck some where. Why was the unit changed out? Was it a leaker was the system full of moisture? Maybe some crud in the piston and it shot into the coil. If it ain't broke now forget about it.
  • Flounder1310
    Flounder1310 Member Posts: 14

    I changed this unit because the compressor on old unit shorted to ground. It was 16 years old and customer had ID coil swapped out last year for leaks. There was not a Dealer of the old unit close by so I called my supplier and ask if he could match a unit to the near new coil. There was no acid or oil in the lineset but I flushed the lines before soldering any joints and then did what we call a triple evac . This is three nitrogen charges pulling vacuum between each of first two charges down to. 30 ins. and last pull down to at least 500 microns. On Mon. We had 60F today we have 27 and about 9 inches of snow. Haven't had a call. Just wanted to know if anyone had seen this and had problems later and what to look for if anything arises. Thanks!
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!