Ruud HP - Goes Out On Reset

[donsabi]

I have an older Ruud package unit I think is 2 ton and probably 20+ years old. Occasionally it will go out on reset and once I reset it the unit runs just fine until the next time it goes out on reset. I have had several techs including a Ruud tech who have failed to correct the problem, but all want to sell me a new unit. I have had the thermostat replaced, several relays, coil cleaned, and compressor charge checked which was OK.
I have had several houses with heat pumps and one thing that is different about this Ruud is the air flow. The fan is really pushing some serious CFM. The return air is so strong it will cause a top-of-the-line air filter to collapse. (I have to use the cheap fiber filters).

I thought the problem might be the fan speed but I could not see how to change the speed. I did disconnect the fan and started the unit. It when out on reset almost immediately.

I seems more prone to go out when the unit sits without running.

I have also been told I have leaks in my ductwork.

The model number is worn off the nameplate but inside I got this number Rheem RXPJ-AA15J but I am not sure if this is a sub-assembly or not.

When the unit runs is runs just fine and my electric usage is almost the same as my neighbor with a similar sized unit on two years old.

Any help is appreciated, thanks.

[garfield]

Sounds like an air flow problem to me. Does the fan always start when it is called upon?

Gar

[nomadpeo]

how long have you lived there ? has the pattern of tripping increased in frequency ? if so, you could have a component going south. it's an old unit. what is the maintenance history ?

the suction on the filter could indicate the return air opening is too small.

i know it's a tall order, but try to find an honest company willing to help you solve your problem. talk to the service manager and ask for the system to be totally evaluated. the fact that the system is old does not necessarily mean it's time to replace it, but if you can find a good service company to help you keep it running and actually solve your problem, they will probably make a sale when it finally bites the dust.

[donsabi]

Thanks for your replies.

I am not sure about the fan running when it trips. It trips mostly after the unit sits for a long period as when the day time temps go up.

I bought this house in last November. Before that it was a vacation home and I don't think the owners used it in the winter. It is possible that the HP was never used for heat before I moved in.

You are so right about a good service company. If I found one they would have a loyal customer in me. I think most just want to sell me a new unit and they surely don't seem to want to take the time to troubleshoot the problem.

The air return is still high with air leaks and this leads me to believe that the problem is along these lines. When I disconnected the blower motor the unit tripped as soon as I started it.

This is a twenty year old unit and I wonder if there is some kind of an air flow sensor involved. (Just guessing as the schematic is not legible).

[nomadpeo]

to be clear, where is this reset button ?

[donsabi]

Reset button is located on the electrical control box that is under the center cover of the heat pump unit. This is a package unit.

To make things easier I have cut a hole in the center top panel and mounted a small sliding door to access the reset.

[nomadpeo]

it sounds like a high (freon) pressure cutout control. poor heat transfer due to poor airflow or restriction on the indoor coil can cause the discharge pressure to exceed the cutout setpoint of this control. it is there to protect the compressor under these adverse conditions. the same switch will trip in cooling mode due to poor heat transfer if the outdoor coil suffers from poor heat transfer. (since it is a package unit, it may be harder for you to discern the difference between indoor and outdoor coils, but the outdoor coil is the one you can see from the outside, if that helps. these coils switch roles when mode changes from cool to heat. ) when you disabled the fan and the switch tripped, you saw the exaggerated example of a heat transfer problem. the switch did its job. when it trips intermitently, you are seeing symptoms of a problem with heat transfer. the high suction of air pulling on the air filter is a clue. it sounds like the return air duct or the return air opening is too small. if it is tested in cool mode, the problem will not trip a high pressure switch because the coil is now being used on the low (freon) pressure side of the system. none-the-less, the heat transfer problem still exists and affects efficiency as well as wear and tear on the compressor.

i would like to get a consensus from others on this theory. there are other, less likely possibilities.

[donsabi]

Thanks to all for your input.

The servicemen who have looked at the unit have told me that my duct work is leaking. One went overboard when he saw the return air duct and the unsealed seams located just inside the filter area. I have also had a rep from the electric company that recommended sealing the ducts and not doing anything to the heat pump and I also had the same recommendation from one servicemen. So two tell me I need a new HP and ductwork and two tell me I need to seal the ductwork and the HP is OK.

This until is probably 20 years + and I must believe that it did work correctly for some time. So how is that the air ducts are now the problem? (I am not being argumentative, just curious). I air ducts are leaking and the return air will cause a good air filter to collapse.

BTW, not one serviceman checked the current draw on the compressor or anything else for that matter. They did check the charge on the compressor and topped it off a bit but said it was alright to begin with.

I would like to change the speed of the blower motor, (slow it down and bit), just to see what happens but I have no idea how to do that.

Fortunately I had only had to reset it once in the last week.

[donsabi]

Thanks to all!

I seem to be in an area where troubleshooting is a language that remains unspoken. As mentioned, I have parts changers and that is about it.

I had a conversation with one who told me when the unit was new the duct work was adequate but after it has aged the duct work is undersized.

I will look into a manometer.

When the unit is tripped the evaporator coil fan is not running. The compressor is. When I hit the reset the evaporator coil fan comes on.

Sorry I am not up on this everyday. I have to travel a few days and I am not at home of the time.

[nomadpeo]

just catching up with this second page. hmmmmm. when the switch is tripped, the indoor blower stops running and the compressor continues to run. i am now wondering what exactly is tripping. can you send us a picture of the tripping control ? in the case of a tripping hpco switch, it would be just the opposite. maybe this reset switch is some overload device for the blower.

dilkey is right, of course. when you read the static in the duct, you will probably see a problem. as you suggested, if the problem did not always exist, then something has changed.

by the way, you said a 'good' filter creates the suction. that stands to reason, since the lower micron filters have more inherent restriction. the phrase 'pushing serious cfm' could be misleading for us. the sound of air sucking through a filter and a filter sucking into the return could also be an indication that the fan could be running normally, but is being affected by restriction on the entering side. it still sounds like a restriction in the return air plenum area. perhaps some insulation has collapsed or something. also, the information doesn't add up. it only does it in heat mode. the blower is what goes off when this control trips. i'm wondering if we are getting correct representation of the problem and identification of the components. i would really like to see a picture of this reset button and what you are describing as the evaporator fan.