Hey Guys, I'm having problems with my HVAC system in the house and need some help. Back in July, I had to have the evaporator coil replaced and since then have had problems. The old thermostat took a dump and I went to Lowes and bought a new one for it. The old one had more wires on it to hook up than the new one does. When I called Honeywell tech support (twice), I got someone in India that I can barely understand. I DON'T think the new thermostat is wired correctly, but both times I called, I got the same answer for the wire connections. The old thermostat had a brown wire connection and the new one says not to use it. The old thermostat connections were (by wire color and terminal connection), Green to G, Yellow to Y2, White to W2, Red to R, Brown to C and Black to E and Orange to O. Now, according to Sayed and John (?), the black and white wire go together on the W2 terminal, then Green to G, Yellow to Y, Orange to W, Yellow to Y and Red to R/RC. The R/RC terminal has a jumper which I was told NOT to remove, so I didn't. They said the Brown wire just needed to be taped off and not used. On the old wiring, there's also a light blue wire that was taped off and not used. Problem is now, the a/c will come on for about 5 minutes and then it shuts down. I had an HVAC guy come and check the system last Friday and he said it's full of freon, there are no leaks in the evap and it should be working just fine. He said he wasn't sure the thermostat was wired right, but it LOOKED okay. It was 85 in our house last night at 10:00 pm and 83 at 11:00 when we all went to bed. Miserable night and it will be tomorrow before anyone will come out to look at things. I'm thinking the damned thermostat is not wired correctly. Can anyone PLEASE help me out with this? I know absolutely nothing about HVAC and am out of money and patience. The system is a 3 1/2 ton Frigidaire system, the house is 1623 sq. ft. The system needs upgrading to a newer, more efficient one, but I just don't have the money to do that.

 

Not me --so I'm the perfect one to take advice from!

Hear we go:
IN THEORY
Red to R/Rc with jumper: Correct. Hot lead from 24v ac transformer by unit
Yellow to Yellow: Correct. Controls cooling part of system.
White to White: Correct. Controls heating part of system.
Green to Green: Correct. Controls fan relay portion of unit.

These should be the only 4 connections you need to run AC+Heating with one BIG caveat. If you have 2 stage cooling or 2 stage heating (like a heat pump or geothermal thing), THEN the Y vs Y2 and W vs W2 start coming into play.

Your previous setup had a black and an orange wire that HAD been connected, AND your Yellow was to Y2 (not Y) and White was to W2 (not W). These are designated as second stage systems, NOT first stage systems.

This and little research tells me you have a reversible heat pump -- that was also wired into the system---SEPARATELY on your older thermostat. You'll need to get another unless this has extra terminal spots for orange and black, which I am assuming were wired up as the PRIMARY stage heating and cooling.

That's not what you want right this second, so my suggestions are:

1) GREEN to GREEN
2) WHITE to WHITE (not W2)
3) YELLOW to YELLOW (not Y2)
4) R to R/Rc jumpered
5) Orange (temporarily disconnected) tape off /wire nut
6) Black (Temporarily disconnected) tape off /wire nut
7) Brown (tape off/wire nut --only needed if thermostat is NOT battery powered
8) Blue (leave taped off)

This configuration should make your HVAC system the PRIMARY stage cooling device in the house. My guess is that by combining the heat pump and HVAC wiring one on top of the other led to a "Ball of Confusion"--that's what the world is today.

Let me know if it works or not. Be sure to shut off power at the HVAC unit as short cycling compressors is not good and can happen accidentally while you are wiring stuff.

If for whatever reason your new thermostat ONLY has Y2 and W2 (no Y or W), use those -- just leave the orange and black outta this for now.

Call me in the AM (**** it's almost dawn) and let me know if I need to so more research.

I know you'd do it for me.

Gnite

PS: There are other causes for system rollouts (shutdowns). Does the unit have a circuit board w a red LED? if so, is it blinking when the air shuts down --and what is the blinking pattern. I assumed it was not modern enough to have one, but I figure it couldn't hurt to ask

Also -- did you change the furnace filter? Clogged filter will make blower motor work too hard and there may be a thermal sensor on or near it

Derf

 

Thanks for your efforts, derf. I DO appreciate all you've done. I kept piddling with it yesterday evening and around 1730 hours or so, I discovered that the jumper between R and RC was missing! Son of a ........... Anyway I couldn't find a paper clip to make another one and grabbed a pin out of Re's pin cushion. As I walked over to the trash can to cut it, I noticed a paper clip lying on the counter. So, I cut a piece off it and bent it. Got to the t-stat to install it and dropped it. Bent down to pick it up and there was the original jumper! Put it in, placed the thermostat back in and fired the system up. It's been working ever since then. It's following the program I set it to and the compressor has been cycling on and off like it's supposed to. A tech from the company that replaced the evaporator is SUPPOSED to come and check it out today, since it's under warranty. It's free, so I'm going to let them come and see WTF is going on with this thing. It's driving me nuts. Someone that does HVAC for a living over on another forum I'm on told me I have it wired correctly and it may just be a capacitor that needs replacing. It could be getting hot and losing contact. I don't know, as you can tell, I don't know anything about this stuff. I sure wish I did.

 

Great to hear!!

Well....I was sorta right about the theory at the beginning....wasn't till I started to apply it that the train partially derailed.

Still would love to know about those orange and black wires......

Very strange.... Armed with my freshly minted knowledge, if you have those orange and black wires in the wall, they were presumably wired to something at the other end. Maybe the Y and Y2 are enabled simultaneously (W and W2 also), so it doesn't matter which system is wired to which set of terminals as long as the 2's and the non-2's are kept together regarding each device.

Well now I know what controls what in my thermostat so it was still a learning experience.

Also --- the capacitor he's talking about is the "Run" capacitor. It stores energy 90 degrees out of phase with the AC input signal's electromagnetic field. By doing so, when it releases it's energy, it helps to keep the compressor and the cooling fan motor (outside) spinning by adding a perfectly timed "push" to the rotational motion. Without this extra push, the motor would not keep spinning, hence the term "Run".

I replace mine every 7 years or so to be proactive.. They are less than $30 and it keeps you from having to pay $100 for an emergency house call and $150 for maybe a $30 part. When they go bad, they start to swell so it is easy to spot an upcoming failure.. Just make sure you DISCHARGE it holding a Metal screwdriver w an INSULATED HANDLE across the terminals before you begin to work on it.

If your system is maintaining set temp with no on-off behavior of the compressor, when there should not be, your run capacitor is OK. I think that comment was for when the sys would run 5 min then stop cooling b/c the run capacitor was possibly going bad and overheating and could not do its job.


I enjoyed this mini educational jaunt into HVVAC.

Please go break some plumbing related stuff. I'm clueless and need to learn that.
Worst part about plumbing is that if you get it 3/4 right, the other 1/4 still pours out on the floor and soaks through to the sealing below. Especially fun with grey water.

Chill out bro, and fed ex me (same day delivery) a Mikes's Hard Lemonade on dry ice so that we can drink together after dinner.

 

hey can you wire it my way and let me know if it works?
Otherwise the world may never know......

I'm sure you're dying to mess with it

 

Baaaahahahaha! That's funny, derf. Hell no. I'm not touching that sum beech again. The odd thing is that it cycles on and off about every 10 t0 15 minutes. I don't know if that's normal or not. Still waiting to hear from the HVAC guy, but I really don't think that bastard is going to even call, let alone come by. Hell, it's after 6:00 pm already.

 

if it is cycling every 10-15 min but NOT reaching the set temp during a single cycle, then there is in all likelihood an additional problem. Could be issue w run capacitor overheating (though I would think it would take much less time to happen). Could be the blower motor overheating. Could be the compressor overheating and shutting itself down.

Have you gone outside and made sure the fan on the outside unit is spinning? This is critical as it not only pulls air across the coils but also helps the compressor dissipate heat. I would think that the guy who filled the refrigerant would have checked that, but then again the thermostat went south after he left, so anything is possible.

Finding the run capacitor is not difficult. Turn off the breaker. Just follow the electrical bundle out of the house and into the unit. The access panels are usually only held in by a few screws. The run capacitor will usually be a cylindrical can or a flattened oval shape, with two terminals coming off the top. If it looks like it is bulging or misshapen, then it needs to be replaced. Again, the service tech filling the refrigerant would likely have noticed this, but you never know.

In any event, if you have a new home warranty, use it to the max.

I'm beginning to wonder if the original thermostat was actually bad, or if the fact that the system being back up and running caused stress on the next weakest component.

You might try removing the orange and black and see if that helps, as it seems you are tying the control of two systems to one set of contacts.

Do you have another heat/cooling source (heat pump, etc)?
What are the orange and black connected to down near the unit?

Also -- did you put in a clean air filter?

_______________________________

For the record, the config I suggested is the current config in my house, minus the orange and black