Central Unit running all day

13 years ago

I have a 2 1/2 ton unit. The outside unit is only a few month old but has just started being used within the last month. The inside unit is right at 10 years old. My problem is that during the day the unit runs from about 10am - 3am. It does not get below 78-80 during the day. The home is a manufactured home and is 1,397 square feet. There is absolutely no shade and the unit is on the west side of the house and we live in Texas. I have had an A/C tech come out an he said the coils are clean, freon is charged, lines that are suppose to be cold are, and he doesn't think there's a problem with the unit. I have been doing some research and decided to check the temps at my supply an return vent. My supply vent is at 69 and my return vent is at 77. What could this possibly mean? We know that when we bought the property there had been some raccoons living in the crossover duct of the home so we replaced it and it is sealed up tight. I also had to replace the thermostat when we moved in because the previous owners took the original one. Another question I have is when we first started using the A/C we noticed warm air coming through the vent when the a/c would shut off. After my husband had to get under the house to repair a water leak he noticed the furnace was glowing, meaning it was on. I ended up figuring out which breaker it was an just shutting it off. What could be the problem there?

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Comments (7)

tigerdunes
13 years ago
Supply temp is way too high.should be in high 50s, low 60s. Could be many reasons including bad refrigerant charge, ductwork leaks, etc. mismatched outside and inside units are never good. You really have not properly identified type of system you have. But a furnace or air handler with heat strip should obviously not operate in AC cooling mode.

At what outdoor temps are you finding the conditions you describe?

IMO

This post was edited by tigerdunes on Fri, Jun 21, 13 at 19:32
Maegan
Original Author
13 years ago
The current outdoor temp was between 90 & 95 when I took the temperature reading at the supply and return vents. I had the refrigerant checked by two A/C techs and both said level was good. I have a feeling it is probably a leak somewhere but we have been all over under the house and could not find one.
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mike_home
13 years ago
If the duct work is in the attic then it may need to be insulated. Is it a hard duct or flexible?
Maegan
Original Author
13 years ago
The duct work is all under the house. The majority of the ductwork is metal but there is one section that is flexible. The flexible duct we have already replaced because a raccoon had been living in it. Since it is a double wide manufactured home they have a flexible duct (crossover duct) connecting the halves of the home.
mike_home
13 years ago
The metal duct work needs to be sealed and insulated. You may also have it cleaned if raccoons were living inside.
udarrell
13 years ago
Of course, the control tstat is/was not wired correctly furnace ought not cycle in cooling mode.

It looks like it may be drawing hot humid unconditioned air into the return air.

An 8F indoor split is totally unacceptable!

Next time; Check the outdoor temp & the discharge air temp coming of the outdoor condenser; at 50% indoor humidity should be around a 20 to 22F temp-rise at 1050-CFM indoor airflow. List all temps & always indoor humidity level...

Your system has serious problems that must be diagnosed ASAP!

Here is a link that might be useful: Charging system using Superheat & Subcooling
WyrTwister
13 years ago
I agree , the thermostat and or thermostat wiring is really messed up if the heat and cool were running at the same time .

My understanding is you have electrical resistance heat ? You turned off the circuit breaker feeding the heat . Depending on the amount of resistance heat you have , it is possible you have a couple of heat strips and a couple of circuit breakers feeding them . For instance a 10 kw and a 5 kw heat strip ?

Or , perhaps you still have not turned off the correct circuit breaker ?

Part of the reason I say that , is , on straight resistance heat with A/C , you usually have 240 VAC feeding the out door unit and a separate 240 VAC circuit feeding the indoor unit . ( Maybe , possibly two 240 VAC circuits feeding the indoor unit , it if has more than about 10 kw of resistance heat . )

Commonly , the inside fan , control transformer and controls are feed from the same 240 VAC feeding the first 10 kw of heat .

If you turn off that circuit breaker , it kills the control transformer , thus the 24 VAC control power and nothing works . ( It is possible , some units may have the control transformer in the outdoor unit , or maybe , even both ? )

So , check this out .

Lastly , it is possible , with multiple heat strips , to run , say , a 90 amp circuit breaker & wire to the indoor unit to feed , say a 10 kw and a 5 kw strip heat . In this case , the indoor unit will have one or more circuit breakers , in the unit , to sub-divide the power . Or , a couple of fuse blocks and fuses to do the same thing .

But , do make sure you get the thermostat wiring straightened out .

God bless
Wyr