Posted on 10/26/2010 3:06:38 PM PDT by LouAvul
I have a 4 ton Carrier unit that was manufactured in 1996. My house was built in 1998 so Im assuming the unit sat in a warehouse for a couple of years. It requires R-22 freon which is being phased out and, again, Im assuming theyll be charging a premium for it.
My air conditioner has been shutting off. It would run for a couple of hours and never reach the target cooling temperature. The outside unit (fan) would shut off and the attic unit (coil?) would continue to operate. Id shut it off and after an hour or two, turn it back on. It worked for awhile after I turned it back on.
The HVAC guy just examined it. The outside motor is running at 1.8 amps. He said its supposed to run at 1.4 amps which means the motor is overheating and shutting off. In the attic he showed me significant level of rust and he said that the coil is freezing which is why theres no air flow when it should be cooling. Then, according to him, the ice melts and drains, which is whats causing the rust.
He says I need to replace the outside motor ($350) and the coil in the attic (on top of the furnace) for $1500.
Or I can go with new. Thats a 24ABC6 condenser, CNPVP coil and 58PHA furnace. This costs $6900. From $6900 I can subtract $1500 for a tax credit, $525 for our local power company instant rebate, another $75 rebate from Carrier, and a $125 rebate from the installer. Thats $4675 installed, plus tax.
The guy also said the warranty is significant. For the first year, emergency service 24 hours a day, 7 days a week. 10 years on parts, compressor, condensing coil, and evaporator coil. 5 years on labor. 20 years on heat exchange. Theyll also install a programmable thermostat. Currently the thermostat is non-programmable.
The IRS is discontinuing the $1500 tax credit after this year.
So I can spend $2000 to fix the existing unit or $5000 for new. The new price includes the furnace as well.
Get multiple bids, even for the same brand.
Make double sure the AC and furnace combination qualify for the tax credit. Make the salesman pull up a tax certificate on the maker’s website showing the combination qualifies. You can get a tax credit on the right furnace by itself (regardless of what AC unit you have), but you have to have the right combination AC unit and furnace to get the tax credit for the AC unit. You may have already been over this with the salesmen, but if not, get it nailed down before you buy.
Get a new unit after getting more quotes. I replaced my entire HVAC back in my old house in 2000 and it was the best. No more hot summers and cold winters in the house!!
Make sure they cleaned your coil. I had the same problem years ago.....the coils were clogged preventing airflow causing the coils to freeze up.
Yes, and short cycle the compessor as the poster described.
Get another bid. If it Ices up it is more than likely lo on freon. The condenser fan motor could be the problem as it is drawing to many Amps. Unless the coil is corroded or dirty it should be good. I have never had to replace a coil. Another tech and remember the Pubbies are more than likely to not continue the tax credits, so you should act while Obama and the Rats are in charge.
The outside motor Could possibly be stopping due to the outside coil being dirty causing the compressor to cut off. It's hard to say without seeing the unit. But the amp reading really dis not that significant. It it was a couple amps over? Yea there might be problem.
The unit is 14 years old sounds like. If you can fix it for around $500-$600 My self I would have it fixed if it were mine. If it is a heat pump? I'd seriously consider full replacement. I am a retired Maintenance Mechanic with HVAC experience. What I told you is just so you can have a general idea of what's working right and what isn't.
As for a new unit? Get several written estimates. A legitimate dealer will not mind doing this and signing a contract when terms are agreed too. It protects both of you.
Wow, finally a topic I know something about. I do HVAC for a living. My two cents. R22 is being phased out yes... In 2020. R22 condensing units were stopped being manufactured this past year. Parts for the existing units will still be made for at least the next five to seven years. Another secret, R410a may not be the next long term refrigerant. It is already being spoken about like the HVAC betamax. My suggestion is to hold off on a new system for a couple of years. The tax credit isnt worth spit when your power company changes seasonal rates. Your system is freezing because it is low on refrigerant. This also causes the larger amp draw. The amp draw you mentioned is less than a full amp? Again nothing to lose sleep over. Tell your tech to pump the system down, pull the evap coil out, clean it, put it back in, put in a new filter dryer, pull a vacuum, and release the freon back into the system and bring it to superheat. Should cost you less than a hundred plus the dryer and maybe a couple pounds R22.
Assuming the system is forced air...change the return air filter. Cheap quick fix to a common problem.
Thanks. I haven’t done refrigeration for years. Your advice to the poster is correct.
1. Verify that the entering air side of your evaporator coil and blower wheel are clean. Your unit is just about old enough to need a good indoor coil cleaning (no filters are 100% effective at removing particulate from the airstream) and a clogged evaporator coil can cause freeze-ups by preventing the heat in the return air from being transfered to the refrigerant evaporating in the indoor coil. Once this is done your supply grills should all be opened fully, your blower motor amps should be noted and compared to the full load amps (FLA) or running load amps (RLA) on your unit’s data plate. You should be drawing at least 80% of the full load amps listed. No refrigerant charge adjustments should EVER be made until the above has been done, as well as making sure the outdoor coil is clean.
2. Your condensing unit will have compressor and a condensor fan motor. Both require capacitors to function correctly. A weak capacitor can cause the condensor fan motor to draw higher than normal amps, causing thermal shutdown of the motor. If your compressor capacitor is weak or fails it can cause your circuit breaker to trip. Condensor fan motorshut down can also be caused by bearing drag. If there is oil visible on the fan shaft side of the motor around the shaft seal or the fan shaft has play it should be replaced along with the capacitor. If the fan blade is still properly balanced it can be re-used.
3. If your unit has a low refrigerant condition your suction line (the larger copper line on your condensing unit) will be warm to the touch. It should be about 55 degrees with a full refrigerant charge. Your compressor will draw lower than normal amps because it’s not working as hard as it should be. It also won’t be rejecting the normal amount of heat out the top of the condensing unit. Leaks can usually be found with a refrigerant sniffer, bubble solution (just like a tire), and a little motivation/patience.
Long story short, make sure your tech is thorough before you spend a ton of cash. There are also direct drop-in replacements now available for R-22 systems. DuPont has “Iceon” and Nucor has “Nu-22”. Hope this helps and good luck!
I think the advice you have been given that it is low on freon and needs to be cleaned is entirely correct so I will not comment further.
Cheers,
knewshound
Get multiple bids, even for the same brand.Make double sure the AC and furnace combination qualify for the tax credit. Make the salesman pull up a tax certificate on the makers website showing the combination qualifies. You can get a tax credit on the right furnace by itself (regardless of what AC unit you have), but you have to have the right combination AC unit and furnace to get the tax credit for the AC unit. You may have already been over this with the salesmen, but if not, get it nailed down before you buy.
+1
Thanks for posting this... facing a similar predicament, got lots of good advice! :)
Went through a similar situation on my 3 ton Carrier last July. The technician claimed it was the fan. After paying for 2 service calls, a new fan, and a new capacitor, I still had almost no cold air. Oops... they forget to mention that the compressor was shot. But they would make me a really good deal on a new system.
I fired the idiot, had somebody else come out that I trusted, had a new 3.5 ton unit installed, and chilled out the rest of the summer.
Definitely get a second opinion from a technician you trust before spending on parts for an old system. And let me know if you decide to replace the fan motor... I know where you can get one (used for 1 day) really cheap.
I assume you’ll be getting a higher efficiency unit - you would have to in order to qualify for the $1,500 - the good news - you can factor a lower monthly bill into your calculations. I replaced my old unit with a Carrier Infinity (18 seer) - and it’s wonderful. Even tells me when to change the filters - when to call for help. Doesn’t brew coffee - but that’s the only downside so far... And it controls humidity levels in the house. For an additional $800 I got a ten year parts and labor total coverage. I’m happy.
Or he could have a freon leak... what’s the pressure reading?
I’m in agreement. Forty plus years in HVAC going back to cast iron compressors. Low R-22 most common.
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