I decided to write this week about a service call I received in Garland, Tx from a new customer that found us on the Better Business Bureau website. It was a tricky one and worth sharing.
She had actually contacted me through e-mail on Saturday afternoon. I contacted her back and she scheduled a service call for Monday morning since it was going to be a cool weekend. She stated that the unit had been freezing up and wasn’t cooling very well. Dirty filters are a number 2 cause of air conditioning freeze-up (number 1 being low refrigerant levels). Her house was an old Fox and Jacobs home built in the early 80′s with fur downs. She stated she was very good about keeping her filters changed and that she had lived in the house for 5 and a half years. She showed me the air filter in the wall in her kitchen area, and it indeed was clean. I then went to the air handler in the converted garage into the “cat room”. The first thing I saw was a E-Z filter base under the air handler and just by habit I lifted the little lid and saw a filter. She said she didn’t even know that filter was there. When she bought the house the previous owners showed her to change the filter in the wall as she had been doing. I pulled out the filter and as you can imagine, it was black. The problem was that when the garage was converted, two returns were added in the additions, a small bedroom and the cat room and a little vestibule. The filter in the wall that she had been changing did nothing to filter these two additional return air additions. Luckily, the second filter was there and for 5 years had been catching all that the first filter missed and the other two return air dirty air. This doesn’t mean that you should double filter your home. Double filtering is actually bad for the system and can cause the blower motor to fail prematurely due to it having to work harder to pull the return air across the TWO filters. But in her case it was a good thing. Another problem that can cause an air conditioning system to freeze up is a dirty evaporator coil. While I had the filter out of the E-Z Filter Base I shined my flashlight up into the evaporator coil and looked at the coil to check it for debris. Amazingly it was clean. Okay, so armed with this information, I started the air conditioner and headed outside to check on the refrigerant level and the outdoor contactor/starter. The air conditioning system was 13 years old, not a bad system, a Ruud. The contactor was very black and charred. A stuck contactor is another cause of a freeze up and while I was evaluating I decided to go ahead and get her a price to replace that to rule it out as a possible cause of the freeze up. After hooking up my gauges I found that the pressures were slightly low and determined that the system must have leaked out a little refrigerant and needed to be refilled. I gathered up my information and pricing and headed inside to talk to the customer about my determination and give her some pricing. She gave me approval for the work and I got busy. I hosed off and flushed out the dirty outdoor condenser coils, installed a new filter in the only the E-Z filter base so that ALL of the return air was covered and removed the filter in the wall. I replaced the contactor and started the system to let it run for about 15-20 minutes so that the condenser coil could dry completely and I could get some accurate readings on my pressures. Now, this is when it gets tricky. I added enough refrigerant to keep it from freezing up, got the suction pressure to 60 pounds and then walked away to let the condenser coils dry. When I came back the pressure was at 48 pounds. Now we’re in a different ball game altogether. I checked temperature differentials inside the house and found that they were at 25, which is way too large. Also the outdoor super heat (temp of the suction line) was freezing cold, telling me that it most definitely didn’t need more refrigerant. I went back inside and took the cover off the evaporator coil section of the air handler and checked out the expansion valve and then also discovered the many feeder tubes inside this coil. So, number one I’ve determined that the evaporator coil is restricted, but number two, there is NO WAY to determine the exact location of the restriction. It could be in the expansion valve or in the feeder tubes. I talked to the customer and told her that the best thing to do, to be done once and for all would be to replace this entire evaporator coil if it was available. Of course the best thing would have been to replace this entire air handler, but the customer had limited funds and this was not an option. I called our local Ruud dealer and found that the evaporator coil was indeed available. I picked it up, and we installed it for her that evening. After the installation, pressures were perfect and the system with cooling great. This customer was a nurse, she worked a 13 hour night shift. Her mother had moved in with her when she acquired the home. Then her son, his wife and his 3 kids lost their home and asked to live with her for a minimum 3 month period. She said that was 6 months ago. Her life was chaotic to say the least. I was glad that Acme Air Conditioning was able to make at least one thing in her life a little easier for her.