Bryant Heat Pump Tripping Internal Fuse

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Old 01-14-08, 08:30 PM
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Bryant Heat Pump Tripping Internal Fuse

I have a Bryant heat pump unit that was installed in 1994. It appears to work fine, except that recently it started popping a fuse.

The fuse is on the unit in the house with the blower. On the outside of the front panel are a couple of breakers. If you take off this panel (4 screws), inside on the right wall is a little solid-state card with a 5 amp, blade-type automotive fuse. This is the fuse which is blowing.

I should have known something was up. We bought the house about 5 months ago, and when we moved in, there were a few blown 5 amp fuses on top of the unit. Anyway, the thing worked on A/C fine through the Fall, and was on heat for the last couple of months with no trouble. Three days ago the first fuse went, and I've been feeding it fuses ever since trying to figure this out.

One guy that wanted $200 just to ring my door bell asked over the phone about the thermostat, and it is indeed likely to be the original one. Inside it are two mercury vials, and it looks all pretty old. He said he was suspicious of that right off, but I'm not sure if that's a factor. Because it's so old, however, I picked up a new one from Homie Depot (sic) and plan on putting that on anyway. Doesn't appear to be too cosmic.

Any help with this would be greatly appreciated. I'm in the military, and having just bought this house, money is not something I have sitting around right now. As long as the fuse is holding, the system works normally, so I just need to figure out what's blowing the fuse.
 
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Old 01-15-08, 04:25 AM
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Update -

After struggling to keep the heat going all night (it's 19F), I kicked on the auxiliary heat at the thermostat. That came on and so far on the current fuse is working. Also last night as I was in and out of sleep, I could hear two stages of heat pump operation. After replacing the fuse, the blower and outside unit would both come back on. After some minutes, I could hear something else kick in. This extra kick-in didn't make the fuse blow, either. I didn't manage to stay awake long enough to hear if that secondary was popping the fuse when it cycled off, or if it even got to do that.

Not sure if this helps, but I'll add info as I stumble upon it.
 
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Old 01-15-08, 11:08 AM
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I just had a similair thing happen

Check inside the heat pump to see if there are any wires that have rubbed to the metal. Especially any against the copper tubing. I just had the same thing happen with the 5 amp fuse and it turned out to be that little thing. Just wrap it with electrical tape and bend the copper wire abit so that it won't rub anymore. Good luck! Hope it is that simple.
 
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Old 01-15-08, 07:02 PM
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That 5 amp fuse is in the 24V set up. Like said check all the 24V wire from the tstat to the blower and on out to the outdoor unit. See that it dont short out anywhere. That kickin later could be the unit went into defrost.
 
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Old 01-15-08, 07:05 PM
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I should be so lucky, but that kind of thing never works out for me.

Interestingly, I've had it on auxilary heat all day, and it's working fine. It comes on for shorter periods because it's actually blowing warm air instead of the wimpy stuff the heat pump usually blows. I'm guessing that because either the extra heat is on or just because it's on for much shorter periods that whatever is blowing the fuse doesn't get a chance to do its thing. The fuse on heat pump only blows after about 1-1.5 hours. With auxilary heating on, the unit is not on for more than 5-10 minutes before it cycles off on its own.

Still looking for help. I have heat so my kids can be comfortable at night, but I don't want to have to run on emergency heat as a matter of course.

Thanks to Todd & Deb for the suggestion.

Edit - Didn't see your post there, Ed. I'll give the wires a look over in the AM. Let me know if anything in this posts gives you any different thoughts.
 

Last edited by iltridente; 01-15-08 at 07:20 PM. Reason: Didn't see Ed's post!
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Old 01-15-08, 08:23 PM
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Dont know where you are are how cold is it there. that big copper line should be hot to warm when the heatpump is on. Now here we tell people that when its down to +15o or +20o.
the unit does a better job to heat the home on EME or AUX.
The cost for the electric heat from the elements is about the same as what you get from the heat pump when the temp is that low outside.

Can be just wires, contactor in condenser ,4 way valve in condenser, in the board where the fuse is, the tstat. in the defrostboard in the condenser. You have a short but where
 
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Old 01-16-08, 08:04 AM
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Well, I took a day off to have a guy come out, and he has some secretary call me at 10:45am to let me know he isn't coming and that I should call someone else. I guess he got sick last night, but let me burn half a day waiting for him to show before someone could let me know that.

And this is the third person to stand me up. So far, I'm getting more help from this blog!

Ok, so I checked around. The outside unit does not run with the aux heat on. So, I guess this is the standard, household electric heat. It would seem to me that if I can run indefinitely on standard electric heat, the problem would most likely be in the outside heat pump unit? I went out and looked at it, but without taking it apart all that I can tell you is that it is pretty iced over. Since this doesn't (or hasn't) happened during warm, A/C weather, could this be the problem?
 

Last edited by iltridente; 01-16-08 at 09:49 AM. Reason: Updated info
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Old 01-16-08, 01:34 PM
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I can tell you is that it is pretty iced over.
Then the defrost board is bad????? Or that is the short ????
 
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Old 01-17-08, 05:21 AM
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Well, we'll find out today. A different guy is supposed to come out this AM. The difference is when I started this thing, I had no idea what the problem was and the guy openly stated he was gonna really have his way with my bank account. Now I have the problem narrowed down to a specific point and can put the guy right on it without wasting money on "troubleshooting".

I'll post the results of the visit today.
 
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Old 01-17-08, 12:53 PM
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Score one for the internet. It is the defrost control board. He has to order the part in, but it's going into deep cold for the weekend, so I'll be on electric heat anyway. Should have the new board put on next week.

And instead of milling around, I was able to take him right out and get him checking that board right away.
 
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Old 01-18-08, 12:47 PM
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Same Problem

Hi Iltridente,
Wow. I have the same exact problem, except it is a carrier unit. You mentioned that the defrost control board was bad. Is this located in the outside unit? Also, how do I determine that this is the problem with my unit? Thanks.
Also, my outside unit is not iced. Does it mean that the defrost board may not be the problem? If not, could it be the contactor? Thanks.
 

Last edited by bharat; 01-18-08 at 01:12 PM. Reason: Typo
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Old 01-18-08, 01:38 PM
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bharat You are better off if you make your own post here.

You dont say what your unit does or dont do????
If you dont have ice on the unit then the board can be ok. The defrost board is in the outdoor unit
 
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Old 01-18-08, 02:10 PM
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Well, here's my process, but bear in mind I'm no expert. Cars are more my thing, but many of the principles are the same.

In my case, I tried to observe the timing of the fuse pop with a particular point in the heat pump cycle. This was usually about 90 minutes after start-up, and because it was a regular interval like that, suggested it was tied to something in the operating cycle. During this 90 minutes, I noticed the heat pump come on, and I heard the defrost cycle kick in. After feeding it fuses for a couple of days, I noticed I never really heard the defrost cycle kick off again. Next, I switched over to backup electric forced air heat. Working this way, the pump did not come on, and I did not ever blow a fuse. This indicated to me that the problem was with the pump unit outside. Last, we looked at the card, and it just so happens that the defrost cycle was set at the 90 minute mark - which is how often the fuse was blowing. Where in the cycle it was popping seemed to have varied slightly, but we tried to manually cycle the defrost. Sometimes it would respond, and sometimes it wouldn't do anything.
 
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Old 01-23-09, 05:37 PM
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Same problem with Carrier Unit

Hi! I have the same problem with my Carrier unit! It got cold here in Orlando the last few nights. I have a Carrier AC unit with Heat Pump and Aux Heat. The unit was running all night. I called the serviceman, and he stated it was my thermostat (newer RiteTemp) He said it was designed for a two-stage system and I have a single stage system. OK...so I bought a HoneyWell as he suggested. I wired it up and programmed it. I have AC, heat, but if I push the heat up more than 3 degrees above the current temp, it's tries to call for aux heat, the thermostat says "waiting" , and then the 5 Amp fuse blows. I changed the setting on the T-Stat to Heat Pump WITHOUT aux heat and it runs fine. Change the setting to Hat pump WITH aux heat, and the fuse blows! I checked all the wires. The serviceman did open the outside unit when he was here - could he have shorted out a wire out there? Please help! Thanks!
 
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