Let me start by saying I know little of home A/C. I have a heat pump, the outside unit is 2 years old and the inside unit is 20. Had the tech out for a routine servicing and he tells me one thing I need is a new transformer. Just so I know I'm not getting ripped off on $200 before I schedule this, is there anyone here who can offer me their thoughts on this?

1. How can they determine if a transformer is going bad? I know what it does but not how they can test it.
2. Should it cost that much to replace it?

Thanks!

 

Sounds kinda EXPENSIVE to me. Most common AC and heater control units use 24Volts AC, so the transformer is a 110 (or 220) VAC input by 24VAC output. It should have a tag on the transformer with the input/output and current rating. (If no tag, check for a schematic on one of the panels adjacent to the control section. Just replace with one that similar input/output current ratings (or higher current rated) that will physically fit in the space available. You may have to change the mounting screws if the base has changed but other than that it is a simple swap.

Keep in mind that some universal replacement transformers will have more leads than the original, but that is OK as you only wire up what is needed and cap off the remainder. One example might be where your old transformer has a 110 primary (2 leads) but the replacement has a 110/220 primary with 3 leads (one is a center tap). Similarily, the output winding could be a 12/24 volt. Again with a center tap lead.

Check at a electric supply house or a shop that sells heating and AC components. The last one I bought for a mobile home unit was around $45 for the part. R&R took 15 minutes as I took out the old one in advance to take with me to the shop for comparison of the physical size and mounting.

To test the old, verivy line voltage going into primary winding (standard precaution apply here) and verify 24 volts ac on the output winding. If not there, the transformer is bad or possibly the thermal fuse (internal to the primary winding stack) is open.
why does serviceman think transformer is bad. It either works or does not and if not, unit will not function at all. Only other problem would be if transformer is very hot to the touch which indicates it is too small for the load.

Dialtone

 

Edit above:

Checked back and the part was under $25

Why does serviceman think transformer is going bad? It either works or not and if not unit will not function at all. Only other possibility is transformer is very HOT to the touch which indicates it is under rated for the load.


Dialtone

 

Yeah the transformer is easy to replace and you can get them even at Radio Shack if you know what you are looking for. I do not currently have a heatpump, but my AC system has the transformer inside the air handler, not out in the yard with the fan and compressors.

One thing that can cause the transformer to go bad is if the relay inside the outside unit goes bad. Bugs, spider, frogs etc often crawl up in there and they jam the relay so it doesn't move it's full travel, this puts a load on the transformer and kapoof.

Good Luck,

Jim Henderson

 

I had a bad capacitor on the fan motor for my A/C. I knew what part I needed, but it was very difficult for me to buy it from a distributor since I'm not a contractor. When they finally did sell me the capacitor, I felt like I was getting it under the table. Better luck to you.

 

I usually find I am treated like one of the guys if I show up a tad grubby, act friendly and know specifically what I want. I sometimes even get the jobbers discount.

Jim Henderson

 

I had everything down but the grubby part. They couldn't believe I knew what was wrong and what part was required.

 

You should try buying parts for gas appliances... I usually HAVE to pay cash, if you know what I mean ...

I've learned the "grubby" thing... helps in auto parts stores, appliances parts, etc

 

And I've learned that the "grubby" thing has the opposite effect in places like banks, restaraunts and schools

 

I don't visit banks, resturants or schools when grubby

 

Yeah, grubby is an exacting science and a tool to be used only when proper.

I remember the stellar service we got at a Dennys one time when me and my buddy showed up in our grubby clothes smelling of fishing bait after one of our Tuna fishing expeditions.

You'd a thought those gals never smelled ocean fresh tuna mixed with anchovies and a couple days of sweat. Heck the holes in our pants did NOT show anything important. And I think they over reacted when they thought the sheath on my belt had a knife, it was my fishing pliers for Pete's sake.

Jim Henderson

 

Oh...so the grubby thing is NOT a good idea as acceptable dress for every occasion? That would tend to explain a lot...! I don't think I even own any "non-grubby" type clothes. -TD

 

The grubby theory is absolutely correct. I never get treated as well in hardware stores and auto parts stores when I am not wearing my work uniform. If they see me wearing my uniform they ask me if I am charging it to the company. I tell them no its for personal use I am paying cash. They give me a good discount anyway. Not to mention they bend over backwards to give me service.( I think this may be due to the fact that the company I work for has expense accounts with these stores that sometimes goes in the tens of thousands each month)

 

I get the same results when I wear my company uniform. I can pay cash & get our company discount at most places. Its quite a difference over retail.

 

like Dialtone stated, it either works or it don't. if it is $200 for the whole service call with changing the transformer is probably about on par but to just change the transformer way too exspensive.