Air conditioning help

[Guest]

I'm having some problems with my central air and hope that someone can give me some ideas about what could possibly be wrong with it. A little over 8 years ago I had central air installed for my mobile home. It's a Nordyne Miller - model #P3RA-036K. It worked great for the first few years. Late last year I noticed that it wasn't cooling the way it should. Half of the vents had little or no air coming out of them. The ones that did didn't do enough to cool the mobile home so the air was constantly running. Being late in the season I decided to hold off having it checked out until this year. I scheduled maintenance on it and they told me that I could run it, if needed, until they came to check it out, which I did. They also said that if there was a problem that they'd get to me sooner. There was the same problem that I had last year so I called them and they scheduled me sooner. Two service calls later, from two different companies, I am out $200 and still don't have working air. The first service tech came out, cleaned the unit, added some freon and proceeded to send me a bill for $150. This supposedly covered the freon and repairs to the unit except no repairs had been done unless you count him screwing a piece of skirting to another or pushing the unit closer to my mobile home. I ran the air and it still didn't work properly. The company and I had a disagreement about what had and hadn't been done and the charges so I contacted a second tech to come out to get another opinion. He came out, took the unit apart and the only thing that he thought could be wrong were with the inner coils. He said they could be dirty so he sprayed some foaming coil cleaner on them and told me to run the air so that the condensation would help the foam clean the coils. Other than that he said everything looked good. I did just what he told me and it still isn't working. It's been hot here and as you well know without any type of working air, a mobile home is like a sauna. Right now I don't have the money to keep having techs come out here to check it out, only to keep billing me and telling me that there is nothing wrong. My electric bill has just about doubled because it is constantly running so that's putting a strain on my budget. I've thought about buying a window unit which is what I used before I had the central air installed but before I pay out any more money I'd like to know if there is something with the central air that the techs overlooked and if it would be more cost effective to try to fix it. I would really appreciate any help or ideas you may have.

[Yanita]

Hi Glake,

I am not a tech, but in your post you said that you are not getting alot of air from the vents...have you checked under your home to make sure the vents have not come apart?

You can also do a check from inside the home, take a small hand mirror and place in the first register, place a flashlight in the next, this should show you the inside of the ducts, do this all the way down the home.

Surely, one of the techs will be here to advise you further.

~Yanita~

[Guest]

The second tech looked under the trailer to make sure that nothing had come apart and he also checked to make sure that the hoses from the air conditioner to the vents were still hooked up. He didn't find anything. The thing is I had no problem during the winter getting heat through the vents and although my air is separate from my furnace it all goes through the same vents. I don't understand how it can work for one and not the other especially when I had no trouble when I first got the unit.

[Yanita]

Hi,

JMO, but some techs are not always reputable, not all certainly want crawl around under these homes.

"Hoses" from the air conditioning, what type of ducts do you have, aluminium or flex duct?

Have you personally looked under your home to see what everything looks like. Most all of your duct work is tucked up under the belly material and the insulation, therefore a tech could not just "look" under and ascertain that there are no separations in the ducts.

Have you changed the filter in the unit within the last 30 days? Have you ever cleaned the coils....

As I said, I am not a tech, just trying to help on the non tech end.

Did you look into the vents with the flashlight and mirror?

Hopefully a tech will come online shortly.

Yanita

[Mark]

I wonder if the motor is starting to fail. Maybe not spinning as fast as it use too? Does the motor get real hot when its running -- like so hot you can't hardly tough it?

Robert will hopefully be back online tomorrow. He took a few days off over the holiday.

Mark

[Guest]

Yanita, I know what you mean about techs. Unfortunately I'm not the most mechanically or technically inclined person and find that most times I have to rely on techs for repairs and hope that they are doing what they say they are.

The "hoses" that I was referring to are two flexible pieces - one is hooked into the vent system to circulate the air and the other is hooked to the return vent. My unit is self contained so the only thing that it and the furnace have in common is the vent system. I know there is a filter in the return air duct in the mobile home and I keep that clean. As for the coils - the first tech came out and supposedly thoroughly cleaned the unit. I say supposedly because I couldn't watch him every minute so I can't say for sure exactly what he did. The second tech sprayed some coil cleaner on the inner coils and was the one that told me to run it so the condensation would help the foam clean the coils. Unfortunately this time they have been no help and what it's coming down to is whether there is something wrong with this unit, finding out what, and then deciding if it would be cost effective to try to repair it.

Mark, I'm not sure what motor you are referring to. Are you talking about the fan located at the top of the unit?

[Mark]

I was referring to the blower motor that pushes the cool air throughout the home. In a split system, this motor is in your furnace.

Mark

[hvac1000]

If you have air moving out of the ducts the motor for inside the house is probably OK.

You said the filter is clean.

You said the Tech added refrigerant (freon) this may not be OK.

If he did not do a sub cooling/superheat test on the system there is NO way he would know weather or not your unit needed refrigerant.

many times a service person will add refrigerant to a system when it is not needed and this can actually cause more problems that you had to start with. A good tech will take indoor wet and dry bulb readings and take a temp reading of the return and supply duct in your home.

Then he will go outside and take a liquid and suction line temperature reading and a intake and discharge temp reading on the condenser. Then he will take a gauge reading and using a formula determine weather the unit needs refrigerant or not.

I would guess to say he probably did none of what I had just mentioned except to put his gauges on and ad refrigerant. So much for the quality of the majority of the service personnel in the HVAC trade.

There is not much that I can tell you to do most of these repairs are no do it yourself friendly and you need a EPA certificate to handle refrigerant.

[Robert]

Hi,

Your inside home furnace blower motor circulates the air through the ductwork in heat mode.

You have a seperate blower motor in a self-contained a/c unit to circulate the air in cooling mode.

You can have air out of the registers, but if it is just barely coming out, the motor ~could~ be running slow.

Here's my first suspicions though.

There are two close off dampers in the ducts. Either or both could not be opening fully.

One should be under furnace and open for heat airflow.

The other in supply flex duct at connection to duct trunkline under home to open for cooling airflow.

Your flex ducts could be torn or sagging/kinked.

Your a-coil could be dirty or have bent fins

Motor could be slow.


Remove return air grille. Take a garbage bag and lay over the opening .

If it's a floor return, places bricks or blocks on each side to hold.


If a wall return, tape or tack to wall on the ends of sides.


Let the bag sag slightly with some give.


Then set t-stat to COOL/AUTO/65* .


Does the bag pull inward strongly, slightly or barely ?


Turn t-stat to OFF.

Then, if flex duct connections to unit are accessible, disconnect the supply duct from outside unit.

Take another garbage bag and place over the unit supply collar and tape it or use zip ties to hold tightly.


Turn t-stat back on set to COOL/AUTO/65*.

Does the bag instantly fill with air and blow up like a baloon ?


If it does and little airflow from registers, the above supply damaper should be first suspect if flex ducts are not kinked.



This is two good tests w/o ever going under the home test blower motor in outside unit.

Turn t-stat to OFF and Fan ON will test indoor blower. See if good airflow is coming out of registers.



Take care and best wishes,
Robert

[Robert]

Hi All,

Just wanted to say I have edited a large part of my above reply.

Was looking back over forums and making sure all had been answered as best I could and just happen to read this one.


I had drove 12 hours non-stop from SC to TN, changed clothes, then went to a new Church planting we are involved in and got home late. Tried catching up on some questions while winding down.


Some of the info was backwards and in wrong places and very confusing. It also would not give answers needed.


I apoligize for this and have corrected it for future readings.


I really try to help all who come here and sometimes push myself beyond my limits.


There was no danger to unit or homeowners trying it, but it may have caused hair loss and eyes becoming crooked trying to decipher it.


Anyway, back to the grind, hope it is helpful from here on.


A special apoligy to the original poster, hope your unit got worked out, if not holler here and we'll take it to conclusion if further info needed.


Take care and best wishes,
Robert

[hvac1000]

Robert

All of us have been in the same boat from time to time. In many cases you have the advantage of still doing work on our types of systems which is very valuable. The older I get the longer it takes me to figure out exactly what might be going on in a system. I just hope the day never comes that I cannot answer questions anymore. I have learned a lot from your answers to questions so you must be doing many things correctly.