Air Conditioner Iced

Question

We've been having air condoning problems where our unit would freeze up / leak water. We brought out a tech to have a look, the indoor and outdoor unit was completely forzen. Once thawed, he said the unit was low on refrigerant and he wanted to look for a leak. After 3-4 hours of searching and no leak found, his 'manager' came out to double check and found the 'leak' in 5 minutes and decided he wanted to replace a coil and a 'blower board' just incase to 'to not take any chances' (our blower works completely fine). A few things to note, the tech said there was little to no refrigerant in the system. He also said he put nitrogen in the system to find the leak.

In an effort to double check, I took a look at the outside unit, turned off the power to our unit, lifted the fan and I noticed one of the wires going to the compressor is disconnected (the wire connecting to the bottom circle-like opening in the picture below). Additionally, all but one of the screws holding down the fan to the outdoor unit are missing, so running the fan, causes strong vibrations.

The exact model/brand of our compressor (different than shown below) is a Copeland CR42K6-PFV.

What I am trying to do now before shelling out hundreds of dollars for a fix that may not be required, is check if the the issue is much more simple than what we're told (my gut tells me it is).

My question is, what are some things I can check/try in order to troubleshoot the icing of the unit? Would plugging in the wire described and adding screws to the unit and turning on the outdoor fan be a smart thing to try? are there any risks to doing so, other than the unit icing?

I appreciate any advice

Answer 1

The icing is most likely really due to low refrigerant. I had similar problems with a slow leak in my heat pump, and limped by for a few years by having it recharged once a year since it was a slow leak. The bill usually fell between $150-300, gradually increasing every year since the leak was slowly progressing. I finally replaced the whole unit last year for $4500, since the refill schedule was accelerating down to 7 months in between rather than 12. (It was a 14 year old system, so that contributed a great deal to replacing vs repairing in my particular situation.)

Nitrogen is a common method for detecting leaks, so your tech wasn't doing something crazy. The new coil they suggested installing is probably the one that's leaking. You could ask to see where it's leaking, since they should have pinpointed the location with the nitrogen test. As for the blower board, they could be taking a shotgun approach to the repair and replacing parts they think could be related, but I can't say for certain, since they've seen it firsthand and I haven't (I'm also not a certified HVAC technician!). The blower could be a contributor if it's not running, since reduced airflow can contribute to icing as well. Try setting your unit on "blower only" mode, and if you get good airflow, that's probably an unnecessary replacement part. Or it would at least warrant further questioning to the repair company if it's really necessary.

I'm not sure what the wire is for without seeing a wiring diagram unfortunately. The fan screws should have no effect on icing, but it's a good idea to replace them. Remove the last one and take it to the hardware store to find a match. (Make sure you flip the breaker off first, since you don't want the unit running without it's fan attached, or spinning up while you're working on it!)

If you really think they're trying to pull one over on you, you could always get a second opinion, but you'll probably be on the hook for another $100+ basic service call fee from the next company too.

Answer 2

Ok number one issue for icing Low Refrigerant. Another cause could be poor airflow - a DIRTY filter.

Now with that said: they replaced the coils (5 minutes and the unit was diagnosed as leaking where the tech previously did not find it) .. Swap the coils out.. change the blower board - can you say shotgun.

Why change the blower board if the COILS had a LEAK! If he really found a leak - there would be ZERO need to change anything else out. Just "to not take any chances" - sorry If you said you found a LEAK .. why are you doing anything more on a Just in Case basis ?

I have seen where the condenser unit was going bad - more specifically a poorly performing compressor - this seems to freeze up both the evaporator(indoor unit) and the condenser (outdoor unit).

A poorly performing Condenser Fan will freeze up a system as well, this could be that maybe it was turning slow (bad run capacitor) or hanging up - seeing as you had only one screw holding the thing in - was it bumping something and not spinning fast.

As for the water leak - your drain pan and drain tube should be cleaned and checked. The drain pan should be set in such a way to allow the water to flow to the drain; your new coils should have come with a new drain pan.

If it was me I would not call that AC company for servicing the system. While I can not say that the coil was not the problem, I have been around service people enough to know some things don't smell right. The mere fact - he just in cased the blower board tells me something is fishy with his leak diagnoses. I wonder if the blowers run capacitor is on that board or separate.. (cause the Just in case stuff will not wash if it is separate because he did not just in case that too. I hope you did not get ripped off ..

Answer 3

Typically there are 2 reasons for your unit icing up. Low air flow and low refrigerant pressure. High pressure drives the low pressure so if the high side is low the low side will also be low. Lower pressure will get the temperature of the refrigerant below the freezing point of water and your indoor coil will freeze. However there will not be enough refrigerant to absorb all the heat so the large return pipe will usually be relatively warm upon return to the compressor. Since the outdoor coil is also frozen I would look to poor heat transfer. Is it below 70 outside or inside? There may not be enough heat to transfer so it goes back unused and gets colder and colder. Most likely it is an air flow problem. A quick static pressure test should see if you are in the ball park. Drill a 1/4” hole at the inlet of the furnace and one between the furnace and coil. Insert a magnahelic gauge, this will measure the static pressure in inches of water column. If the static pressure is above .6 or so there is some sort of obstruction. Could be the ducts were never sized right, dirty filter, dirty coil, collapsed duct or closed dampers. If it is really low there is a blower problem. Either not running at the proper RPM due to bad bearings or bad capacitor or something is stuck in the blower wheel. It should be obvious if it is running too slow and obvious if something is stuck in it. I once found a ball cap sucked into the blower wheel????