Spring Cleaning — Part 2


It has been a week since my last post, Day Light Saving started, and the temperature has been getting warmer.  At least around Chicago, the temps have managed to get into the 50’s.  Now, this temperature is still not where we want to be to do proper spring start-ups, but every day more snow melts and we get a little warmer.  Soon we will have warm enough temps to do our spring cleanings.

So lets continue on my check list of items.  As a reminder, we did a lot of electrical checks with the power off  in my last post. There are a few more things to check with the power off before we turn the unit on and run it.

Since the unit sits outside and can have a lot of ice and/or snow on it, we want to looks at a few things. For both air conditioners and heat pumps, inspect the outdoor coil and see if the fins have been damaged from ice or snow (or home owners blowing snow on the unit). If there are bent fins, straighten them out so we get proper air flow through the condenser.  Make sure nothing is restricting the outdoor unit air flow.

Overgrown Unit

Look for signs of refrigerant leaks. Are there signs of oil on the coil? Look at the refrigerant tubing and separate any that might be touching since vibration could eventually cause leaks at these points.

On air conditioners, we need to look at the outdoor fan and blade.  Is the blade “bent” from snow or ice? Does the motor and blade spin freely? (heat pumps run in winter but this should be checked to make sure there is no damage to the blade).

So, are we ready to turn the unit on and check it out at this point? Everything we have done to this point has been with the outside unit.  We also need to do some checks on the inside unit before we start this unit up.  If you have been a follower of my posts, you know I am constantly saying that HVAC equipment has to be looked at as a SYSTEM. So, just making sure everything was ready with the outdoor unit was done, we now need to look indoors at that part of the SYSTEM.

Regardless of whether the indoor unit is a furnace or an air handler, we need to look the indoor coil, drains, and air flow. We need to check the air filter in the indoor unit and replace it (or let the home owner know it need replacing).  Is the blower clean? Or is it restricted due to “lack of filter maintenance”? We need to check the indoor air flow CFM (see my post on checking air flow).

dirtywheel1

If possible, check the indoor coil for dirt build up on the inlet side of the coil and clean or vacuum as necessary.

dirtycoil

Check for signs of refrigerant leaks at the metering device and where the line set is attached to the coil.

Inspect and clean the condensate drain system. Check the condensate pump if the unit has one and clean or treat with chemicals as necessary. Make sure the indoor coil drain pan properly drains. If the unit is equipped with an overflow safety in the condensate pump or in any auxiliary drain pan, make sure it is functioning properly.

The last things we need to do before we turn on the unit is to get some basic temperature  readings.  We need to know the INDOOR WET BULB AND DRY BULB temperatures and we need the OUTDOOR AMBIENT temperature. We need these so we can do proper super-heat and sub-cooling once we turn the unit on. These combined with proper indoor air flow will help you determine proper charge in the unit.

At this point, the unit should be ready to be turned on and we can finish our maintenance check of the unit.

In my final post in this series, I will finish the spring start-up of  air conditioners and heat pumps. I also have a few ideas of things that I am sure most techs forget to check. So stay tuned for PART 3 of Spring cleaning.

 

 

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About yorkcentraltechtalk

I have been in the HVAC industry most of my life. I worked 25 years for contractors on anything from residential to large commercial boilers and power burners. For the past 23+ years I had been employed by York International UPG Division ( a division of Johnson Controls) as a Technical support/Service Manager but I am now retired. One of my goals has always been to "educate" dealers and contractors. The reason for starting this blog was to share some knowledge, thoughts, ideas, etc with anyone who takes the time to read it. The contents of this blog are my own opinions, thoughts, experiences and should not be construed as those of Johnson Controls York UPG in any way. I hope you find this a help. I always welcome comments and suggestions for postings and will do my best to address any thoughts, questions, or topics you may want to hear about. Thanks for taking the time to read my postings! Mike Bishop
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4 Responses to Spring Cleaning — Part 2

  1. dsomerv says:

    good info + great photographs …

    considering that, when in heating mode, the indoor unit contains the condenser, is it ever confusing to speak of the outdoor unit (functioning as an evaporator) as the condenser, e.g. “proper air flow through the condenser”.

    • with heat pumps — it is always best to refer to “indoor coil” and “outdoor coil”. Beside heating and cooling, there are times in the heating mode when the unit is in defrost, that the reversing valve turns the inside back into an evap and the outdoor to a condenser. In the heating mode, when the indoor coil is the condenser, air flow is critical so you don’t trip the high pressure switch. Most manufacturer’s specs list the proper TEMPERATURE RISE for a heat pump in the heating mode. Air flow on the outdoor coil in heating isn’t adjustable but that is also why there is defrost mode.

  2. dsomerv says:

    Typical manufacturer’s advice seems to be not to run the heat pump in heating mode above ambient 65F .
    Sub-cooling tables typically run from ambient 65F to 125F.
    So it seems like one has to pick the perfect day to measure both the super-heat and sub-cooling on the same visit ?
    Also, perhaps in part 3 you’ll expound on exactly what should be learned from super-heat and sub-cooling measurement(s).

    • You are correct about not running a heat pump in the heating mode above 65 degrees. However, if your super-heat and sub-cooling are correct for cooling, then there should be a proper charge in the unit for heating also.

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