Replace heat pump unit with A/C only unit

[ike1562]

Has anyone replaced a heat pump with an A/C-only model?

I had a Coleman 48004-969, ducted. I've ordered a replacement unit Coleman 48203-969.

The former is 15K BTU and the latter is 13.5K BTU. We can save discussions about whether I'll regret going down in BTU. This was a mostly monetary decision since the units are about $200 cheaper (15K HP to 13.5K A/C only) for what I consider an overpriced item anyway. The old one was only 6 seasons old and had a soft copper line snap. Yes, snap.

Anyway, I feel that the control box will be fine and not know what's missing. The plug will be the same with fewer pins, I would think, due to the lack of a heat pump.

Do you think this will be okay? Will the thermostat be fine as well, even if it's slid to "Elec Heat" position? I figure nothing will happen if there's nothing to turn on.

I guess I might need to disconnect a couple of 12v wires going into the control box and maybe even on the back of the thermostat.

Thank you.

[gljurczyk]

Originally Posted by ike1562

Has anyone replaced a heat pump with an A/C-only model?

I had a Coleman 48004-969, ducted. I've ordered a replacement unit Coleman 48203-969.

The former is 15K BTU and the latter is 13.5K BTU. We can save discussions about whether I'll regret going down in BTU. This was a mostly monetary decision since the units are about $200 cheaper (15K HP to 13.5K A/C only) for what I consider an overpriced item anyway. The old one was only 6 seasons old and had a soft copper line snap. Yes, snap.

Anyway, I feel that the control box will be fine and not know what's missing. The plug will be the same with fewer pins, I would think, due to the lack of a heat pump.

Do you think this will be okay? Will the thermostat be fine as well, even if it's slid to "Elec Heat" position? I figure nothing will happen if there's nothing to turn on.

I guess I might need to disconnect a couple of 12v wires going into the control box and maybe even on the back of the thermostat.

Thank you.

I can’t see why it wouldn’t work, you would have to disconnect the reversing valve wire from the stat. Remember that stat also controls your propane furnace.

[jaysheridoc]

While I haven’t replaced an a/c unit in a RV, my profession is HVAC, so maybe I can help a little.

In regards to your thermostat question. If there is no connection to the terminal, that controls the electric heat, nothing can happen when you select the thermostat to electric heat.

Heat pump and straight a/c thermostat stats differ based on a heat pump thermostats control over the reversing valve (needed to convert straight a/c to HP). Traditionally the Y, or yellow circuit, is used to energize the compressor and that is typical for HP as well as a/c. In short, HP stats can be used for straight a/c, and some additional work is needed to get an a/c stat to work on a HP.

I doubt you’ll ever notice a 2,000 btuh difference...

[ike1562]

Originally Posted by gljurczyk

I can’t see why it wouldn’t work, you would have to disconnect the reversing valve wire from the stat. Remember that stat also controls your propane furnace.

Thanks for your response. I did unplug the "heat" wire from the control box, but didn't touch the back of t-stat at all. Testing was limited to the fan works at both speeds (cold in Colorado still) and I did slide the switch to "Elec Heat" but nothing happened of course, except a "click" in the stat, indicating it wanted to start something. Nothing happened, not even furnace coming on. The furnace comes on like normal in "Gas Heat" position. I don't see why I need to open up the t-stat.

Also, there was a freeze sensor connected to control box (other end was jammed into fins), which I unplugged both connectors, thinking the new one would have one. It didn't.

Do I need the freeze sensor if it's just A/C or is that for the heat pump only model? I still have the wires to use if it's necessary.

Thanks again.

[ivykrewe]

It should last longer than that. My 3 are 15 years old. If it was mine i would repair it. I repaired one for a friend about 5 years ago and it is still working great.

[ike1562]

Originally Posted by jaysheridoc

While I haven’t replaced an a/c unit in a RV, my profession is HVAC, so maybe I can help a little.

In regards to your thermostat question. If there is no connection to the terminal, that controls the electric heat, nothing can happen when you select the thermostat to electric heat.

Heat pump and straight a/c thermostat stats differ based on a heat pump thermostats control over the reversing valve (needed to convert straight a/c to HP). Traditionally the Y, or yellow circuit, is used to energize the compressor and that is typical for HP as well as a/c. In short, HP stats can be used for straight a/c, and some additional work is needed to get an a/c stat to work on a HP.

I doubt you’ll ever notice a 2,000 btuh difference...

Thanks. The control box was labeled and the "Y" connector was the one labeled "Heat", although it wasn't a yellow wire. That confused me for a moment but I decided to disconnect that terminal only (even if it was a different color), for the moment, aside from the freeze terminals. I did remove those but the new unit did not come with that wire so I'm not sure if I need it.

Thanks for the vote of confidence in the 2K drop. It uses less power too, which some of us can use at times with additional appliances at same time.

I noticed that the new one has only a smaller copper line running through the same zone as the old one. That bigger one is the line that busted. See sideways pic. It seems to be 7/16" soft copper. I soldered with two 45's 3/8" rigid fittings to fix it before deciding that I didn't want to buy the other equipment needed, nor roll the dice on a hundred bucks worth of R410. That, and I don't have the skill. I got only one guy to give me a number and it was $550 dollars to "maybe" get it working again. Yes I know they're usually braised, but read that soldering can work too, just not as strong. I had used a 3% silver solder before giving up.

[ike1562]

Originally Posted by ike1562

Thanks for your response. I did unplug the "heat" wire from the control box, but didn't touch the back of t-stat at all. Testing was limited to the fan works at both speeds (cold in Colorado still) and I did slide the switch to "Elec Heat" but nothing happened of course, except a "click" in the stat, indicating it wanted to start something. Nothing happened, not even furnace coming on. The furnace comes on like normal in "Gas Heat" position. I don't see why I need to open up the t-stat.

Also, there was a freeze sensor connected to control box (other end was jammed into fins), which I unplugged both connectors, thinking the new one would have one. It didn't.

Do I need the freeze sensor if it's just A/C or is that for the heat pump only model? I still have the wires to use if it's necessary.

Thanks again.

Okay, I found out after testing (warmed up here today) that, yes, I do need that freeze sensor hooked up. Fan ran but compressor wouldn't kick on. Hooked it up and it works fine.

[ike1562]

Originally Posted by ike1562

Thanks. The control box was labeled and the "Y" connector was the one labeled "Heat", although it wasn't a yellow wire. That confused me for a moment but I decided to disconnect that terminal only (even if it was a different color), for the moment, aside from the freeze terminals. I did remove those but the new unit did not come with that wire so I'm not sure if I need it.

Thanks for the vote of confidence in the 2K drop. It uses less power too, which some of us can use at times with additional appliances at same time.

I noticed that the new one has only a smaller copper line running through the same zone as the old one. That bigger one is the line that busted. See sideways pic. It seems to be 7/16" soft copper. I soldered with two 45's 3/8" rigid fittings to fix it before deciding that I didn't want to buy the other equipment needed, nor roll the dice on a hundred bucks worth of R410. That, and I don't have the skill. I got only one guy to give me a number and it was $550 dollars to "maybe" get it working again. Yes I know they're usually braised, but read that soldering can work too, just not as strong. I had used a 3% silver solder before giving up.

Okay, I got some things wrong. A few corrections: The "Heat" connector on the control box is "W" but the wire IS yellow. See, I told you I got confused! And it's only 1500 BTU reduction, not 2000. The new unit is 13.5K. Thanks again.

[ike1562]

Originally Posted by ivykrewe

It should last longer than that. My 3 are 15 years old. If it was mine i would repair it. I repaired one for a friend about 5 years ago and it is still working great.

It ought to, but didn't. The one you fixed, did it have a complete refrigerant line break? You must have the vacuum and other equipment, and the skill. So that makes all the difference. Your friend got theirs fixed for the cost of refrigerant and a couple beers, I'm guessing. I wasn't lucky enough to have a friend in the biz.