re: Carrier Weathermaker 9200 CAC not cooling like it used to

[Snowman53]

Hello:

I live in a 1950 Cape Cod Style home. When I bought the house 8 years ago I replaced the furnace and added Central AC, a Carrier Weathermaker 9200 (theoretically 92% efficient.)

Not sure of the BTU or tonnage rating on the AC unit.

Anyway, until three summers ago even on the hottest days I could come home and turn on the AC, set the thermostat at 65 degrees farenheit and in 30 minutes the house was so cold you would need a sweater. So I'd turn it off and was fine until the next day at 5 PM.

Ohhh..the home is two stories and 5 bedrooms with a finished and heated and AC's basement, but I keep all the vents closed except for the main floor as I have all I need there including 2 bedrooms and the master bath.

OK, last summer was quite cool so I used the AC once or twice and didn't think it was efficient as it had been but was not sure--until this summer.

Called a very reputable local HVAC company and the tech arrived.

My gut feeling was that there was a small leak. He hooked up his gauges and said all was well and that the pressure was fine, no leaks.

It was a hot Friday morning when he arrived and most companies said it was a two week wait for service but they got here in two days. The tech was a nice guy and I know enough to ask the right questions but got at least one answer I didn't like. I had the thermostat set at 60 degrees and it was only blowing cool at the vent (70 degrees f.) He services the system and tells me never to set the thermostat below 70f as the system could frezze up.

Feels a bit cooler after he leaves (94 degrees outside and 83% humidity) but after a few hours the house is still not COOL and the AC is running constantly. I put a digital probe at the vent and temp was 68 degrees.

Well, I am still not sure about that. Anyone know what the high and low side pressure should be on this system?

Had I known that all he would do is hook up gauges, tell me the pressure was OK and that all it needed was the coil cleaned I could have done it myself.

System uses R-22 but I still have gauges for automotive R-12 and the fittings are the same.

I can buy coil cleaner for $5 and he charged $48 for cleaning the coil (what I refer to as a condenser)

Anyway, the system is acting exactly like my Volvo did when it had a very tiny leak in the condenser. Took it to two different shops and both said R-134A level was fine according to the gauges. Finally hooked up with a friend who really knows AC (is an R&D engineer for Carrier Corporation) and he immediately said it needed more R-134 and leak detection. We did replace the condenser and he recharged it by weight--not by what the gauges said.

One month of really hot and humid weather later and the AC blows so cold in the Volvo I have to turn it off at times--even on a 96 degree day with 80 % humidity.

That's how the house used to be. I really could get home at 5 PM on a miserably hot day and run it for 30 minutes and then turn it off until the next day.

The company who did the work has been around for years and are reputable, so I know I won't have a problem getting them back here at no charge to do the job right (although I will pay for R22 if needed as I was not charged for that, but won't pay for another service call.)

ANy tips appreciated.

Regards,

Snowman 53

[DNT1]

Very few techs will take the time to do a superheat/subcooling check and as you said the guage readings are not a good way to check charge level. Call someone else and do a interview over the phone before you watse any more of your time and money. Question #1 Do you check and verify Airflow CFM and duct static pressures Question #2 Do you check charge level by superheat/subcooling method #3 Will I be furnished with a copy of the report that lists the above plus the amperage draws of the compressor/condensor fan motor and blower motor? If you get good confident yes answers you better be checking their pricing cuz doing it right takes a bit more time and does cost a bit more than the average blow and go guys but it is worth a few more dollars to have a properly charged system. It is very important that the airflow be first verified before moving to the next step without proper airflow the superheat/subcooling numbers will be worthless and could lead to a severe overcharge.

[Snowman53]

Hello DNT:

I appreciated your quick reply and apologise for not responding sooner.

That said, the info you gave me was indeed helpful and led me to do some more research.

Have not had a chance to talk to my friend who is an engineer at Carrier as he is on vacation.

But I did do a Google on the superheat/subcooling test and see it is the ONLY way to accurately determine whether or not a system needs a recharge. ANy chance you could explain to a neophyte what that test involves and why it is accurate?

Now, I'm not overly concerned about the ducts and vents as I had them cleaned and then sealed all joints myself with an elastomeric coating last year. I can feel plenty of airflow.


What bothers me is that the company who did the work is not being cooperative. I had told the tech at least three times that I felt it needed a recharge and leak detection.

Called them back last week and was told "make sure you are not setting your thermostat below 71 degrees as that is often the problem. Now that is a big stinking pile of manure as far as I'm concerned on this particular system.

Then the girl says "and who will be responsible for this?" I incorrectly assumed she meant the address as my Dad and I have the same name she meant which address. Then I realized she was telling me that as they planned to charge another $50 fee for a service call. Once I got that out of her and made it clear I had no intention of paying twice she got very snippy. I did make it clear that I'd be happy to pay for any refrigerant needed or a superheat/subcooling test but that was it. She told me her boss would call me back. Two weeks later and several polite calls from me to them not a thing has happened.

So, I sent them a letter today via certified mail and indicated if I did not hear from them by Monday I'll hire a competent company and recover what I paid them (original contractor) in small claims court. As busy as I am that is the LAST way I would like to resolve the issue but they have backed me into a corner.

Spoke to a neighbor yesterday evening and explained the issue. He's an engineer and was stunned when I mentioned I'd use small claims court if necessary. So I said to him "Kevin..why don't you go in the house and come back out and give me a $100 bill." He looks at me and says "but why?"

I said to him "see my point now?"

Sad part is he told me if he were in the same situation he'd just eat the $100 and pay someone else to do it right--and a lot of companies count on that.

This particular company counted wrong this time. Never Pi** off an Irishman and cheat him.

Now I find out from a neighbor who had been on vacation that he'd had the same company over to look at his furnace (fairly new and basic service) four times and after that he gave up and called someone else.

BUt he never took them to court for redress. I am not in the habit of suing companies and have only brought two lawsuits in my life (am now 51 yrs young) but this time I will sue unless they fix it right. It's not rocket science--it's customer service as the real issue.

Oh, if this helps anything: the unit is a Carrier Weathermaker 9200 and I have an Aprilaire whole house dehgumidifier installed (works great and was worth every penny.)

Model number of the outdoor unit is: 38TKB036310 (Carrier)
Indoor TXV: 15.3 RLA (whatever that is)
High PSI 300
Low PSI 150

Thanks for listening to my rant--but many thanks also for letting me know what questions to ask. Heck..money was never the real issue on the initial call. If they had told me "we have to do certain tests and may have to add R22 and it might be as much as $300" I'd have said "Fine, let's do it."

All I wanted was the AC and the furnace serviced and wanted to be cool and comfy.

[hvac01453]

not setting the thermostat below 70F is absolutely sound advice. The evaporator coil is 40F colder than the return air temp= 30F...So when warm moist air hits a cold coil it will many times build a small amount of frost on the coil but defrosts during the off cycle. Closing off registars is not a good idea. Your circumventing all the loads that were designed into the system. If your system was properly designed it should only give you a temperature difference measured at the air handler of 17-21F. If it does just let it run. If it takes only 30 minutes to cool the house to 70F from lets say 85F and the outdoor temp is 93F, the unit is too big. This year in MA the days over 90 is phenominal... Last year I think we only had 1 or 2 days over 90F...and the previous years were even cooler. Keep in mind if the unit was matched for the load exactly...on a 90F day the unit won't shut off at all. If your load is 24,000BTU/HR at a 20F temp difference, and you have a 2 ton unit...on a 90 F day to maintain 70F would run continuous. Most companies plug in a fudge factor of 10-15% for a hot day. In MA the temp AVG is calculated for three days over 90/YR. If the suction line is cold and sweating and the condensate line is dripping water, it likely running OK. I think your chasing a ghost...Gas pressures tell you if the coil is dirty on a hot day. If you have a TXV you should also have a sight glass. This would reveal if your charge was up to speed (like in cars)...

[james curry]

yeah closing the vents in the house is a no no , and will eventually burn your run capacitor out and then your fan, swwn it many time before.
the system is desighned to breath easy but have a little back pressure too. check this out i went to a guys house in fl, and replaced the fan motors on a 2 month old unit , i was already like ok ! why this ?
so i replaced the fan and about 3 months later it burned again , now im like somethings wrong, not just a factory defect. i was looking around and what i didnt know was that the owner had just got new carpet and his return air was not coming under the door and the amp draw on the motor was way higher than normal , it took me a while to show him the science but he was eventually convienced , i said look at you voltage with the doors closed , now look at your voltage wth the doors open , the draw was way less , he was facinated i guess but i didnt hacppen again after he shorten his doors , his new pad was to thick , so dont close the vents not a goood idea