A/C not blowing cold.....

[LakeTravis]

Went out to the lakehouse today and turned on the A/C. Noticed after about 10 minutes that it wasn't blowing cold - it has been working great every weekend up until today.

Checked the compressor outside (Rheem 4 ton 14 SEER). The compressor was running (hot to touch), condensor fan was running and blowing cold air, both low and high side tubing felt ambient to touch.

Same thing happened a couple of years ago when the expansion valve was blamed and replaced.

I've called the same service company to come out and take a look at it this week, am wondering if there are any A/C people here who might have an opinion?

 

[FIREd]

Low refrigerant pressure due to a leak maybe?

 

[frayne]

Low refrigerant pressure due to a leak maybe?

My thoughts as well.

 

[RunningBum]

Back when I lived in the Austin area, I heard stories of kids huffing freon. They'd get high, you'd get warm.

 

[gauss]

Was the compressor actually running, or was it just buzzing?

I have had problems where the start-run capacitor went bad and the compressor would not start but just buzz.

One way to confirm that the capacitor is in good order is to:

#1) remove power to ac unit

#2) put a DC voltmeter across all the capacitor terminals to determine if there is any remaining charge in the capacitor.


#3) if significant charge still exists (ie > 20 Vdc) in the cap, discharge it either with a screwdriver blade or more properly with a set of aligator clips with a 1k resistor in series. Observe the charge bleed off by watching the meter.

#4) Once the capacitor is out of the circuit and complete discharged, place the multimeter into resistance mode on the highest resistance setting (ie 2 MOhm)

#5) A properly functioning capacitor will start at 0 ohms resistance and increase up to a very large/infinite value over time.

If you think that your capacitor is bad, Grainger stocks common replacement caps for reasonable costs -- the only problem is that you need to make purchases on a business account (I always referenced my MegaCorp's account together with a cash purchase).

Note I am not an A/C professional, but rather an frugal guy who likes to repair his own stuff. The above description may not be complete or totally correct. You are responsible to verify any information given to protect your hardware and your own safety.

-gauss

 

[samclem]

Just to check: You say "the condenser fan was running and blowing cold air". The condenser fan (the one outside) should have been blowing hot air out of the unit. That outside fan was running okay when the compressor was running, right?

 

[LakeTravis]

Yes, the outside unit was blowing cold air as opposed to the hot air it should have been blowing if it was properly removing the heat from the condensor coils.

The capacitor is good, both the condensor fan and the compressor are running although the compressor was getting hot to the touch - I didn't let it run long enough to tell if the low-pressure cut off would have shut down the compressor before it was damaged, nor did I remove the caps on both of the freon lines and push in on the valves to see if there was actually freon in the lines.

I'm a bit hesitant to think that it suddenly lost all freon since the weekend before it worked fine - but I suppose that is possible.

More likely the expansion valve they replaced a couple of years ago is stuck and not allowing freon to flow to the condensor. Curious to see what they tell me when they have a chance to check it out.

 

[rbmrtn]

I'm a bit hesitant to think that it suddenly lost all freon since the weekend before it worked fine - but I suppose that is possible.

That is exactly what happened to mine. Small pin hole leak in compressor. Working one day, nothing the next. It would not stay charged when they filled it. They had a "sniffer" and detected where the leak was at.

 

[HighRoller]

That is exactly what happened to mine. Small pin hole leak in compressor. Working one day, nothing the next. It would not stay charged when they filled it. They had a "sniffer" and detected where the leak was at.

Same thing happend to one of my AC unit's a few years ago.

 

[FIREd]

I'm a bit hesitant to think that it suddenly lost all freon since the weekend before it worked fine - but I suppose that is possible.

It could be a slow leak and once the pressure falls below a critical threshold, the system suddenly stops working properly. That's exactly what happened to my old A/C unit. It had a very small leak in the condenser and it would take about a year for the pressure to drop below the threshold. But when it did, the system would stop working all of the sudden.

 

[nwsteve]

We have a similar situation when we change over from heat to cool. Apparently there is a switch that regulates but it does not always reset. Tech manually reset on his service call. However, he told me I could do the same thing by simply flipping the power off and letting the system reboot when power is restored.
May not work but can not beat the cost.
Nwsteve

 

[LakeTravis]

Well, it turns out that it IS a leak - the condensor coil in the outside unit is leaking.

It's a 4 ton, 12 SEER R-22 Rheem unit and they haven't confirmed yet but they are thinking it will be around $3K to replace it - and almost a full third of that is for R-22 refrigerant which is roughly $70 a pound.

There is a slight possibility the unit is still under warranty, it will be 10 years old in 3 months and Rheem has a 10 year parts warranty IF the unit was registered within 2 months of installation, otherwise the warranty period is only 5 years.

I can't remember if we registered the A/C unit after we closed on this new house in July 2003, but......I'm obviously hoping we did...

 

[sailor]

It's a 4 ton, 12 SEER R-22 Rheem unit and they haven't confirmed yet but they are thinking it will be around $3K to replace it - and almost a full third of that is for R-22 refrigerant which is roughly $70 a pound.

Wow, that's a good markup for your HVAC tech.
30 lbs jugs of R-22 go for about $450 locally.
Your 4 ton unit total charge should be maybe 15 lbs.

 

[LakeTravis]

Wow, that's a good markup for your HVAC tech.
30 lbs jugs of R-22 go for about $450 locally.
Your 4 ton unit total charge should be maybe 15 lbs.

Wow, you're not kidding - I did a few searches on Austin Craigslist and came up with plenty of R-22 for way less than $70 a pound. Going to have to ask them why they are so high, calls everything else they quote into suspicion. Disappointed to see that, I've used this outfit several times over the last decade as they are right down the street from this property and their pricing was always fair.

 

[gauss]

When I worked on the capacitor problem that I described above, this was after the HVAC techs called it a bad compressor and wanted to sell us a whole new outside unit.

I suspect many of the HVAC techs would rather have you pay them to install a new unit as opposed to repair an old unit due to the higher likelikhood of callbacks on the repaired unit.

-gauss

 

[FIREd]

It's a 4 ton, 12 SEER R-22 Rheem unit and they haven't confirmed yet but they are thinking it will be around $3K to replace it - and almost a full third of that is for R-22 refrigerant which is roughly $70 a pound.

Wow! When I had my system refilled in 2006, the HVAC tech charged me $10 a pound for R-22! I had a 4 ton, 12 SEER system too.

 

[DeborahB]

For that price... what would a new unit cost? There used to be tax advantages to getting a new "efficient" appliance but I don't know if they are still there.

 

[wmc1000]

wow - i replaced my entire 20 year old HVAC unit in Feb with a 96% efficient condensing gas furnace and 13 seer 3 ton A/C for less than $4500

 

[rbmrtn]

Wow! When I had my system refilled in 2006, the HVAC tech charged me $10 a pound for R-22! I had a 4 ton, 12 SEER system too.

EPA has declared war on R-22, it supposedly has tripled in the last year to 70-90 /lb. I replaced a compressor in '11 and the whole job was ~$1300, hope it last another 10 yrs...

Supposedly there is R422D which is a direct replacement for R22

R422D, The R22 Replacement - YouTube

 

[Elbata]

Yeah, a 30lb can of freon now is almost $500. And to think it used to be so cheap, it was used to clean the coils.

Are you sure the compressor is running? Even though the fan is running, the compressor might not be.

BTW, here's <a href="http://www.diychatroom.com/">a diy chatroom that you might enjoy</a>

 

[LakeTravis]

EPA has declared war on R-22, it supposedly has tripled in the last year to 70-90 /lb. I replaced a compressor in '11 and the whole job was ~$1300, hope it last another 10 yrs...

Supposedly there is R422D which is a direct replacement for R22

R422D, The R22 Replacement - YouTube

Yet I can look on Craigslist and people are selling 30lb canisters of R22 for $400.

I've also found and talked to several licensed A/C techs this afternoon after verifying their license on the TACL website - all of them are around the $1500 mark for supplying and installing a replacement 4 ton 13 Seer R-22 unit (including freon).

And I've been able to find new Goodman/Rheem/Ruud units online for around $1000, so $1500 installed with freon rings true to me.

Now I want to know why my "buddies" are quoting me twice that. I'll find out tomorrow when they are supposed to call and give me a firm quote after they've run the serial number to see if the unit still qualifies for warranty replacement.

 

[John Galt III]

Lake Travis,

Has any contractor tried to tell you you need to replace the inside unit also, due to changing from "old" freon to "new" freon, and there being a compatibility issue?

Just curious, because I heard some of that talk a few years ago when I was researching replacement cost for my outside heat pump / ac unit.

 

[LakeTravis]

Lake Travis,

Has any contractor tried to tell you you need to replace the inside unit also, due to changing from "old" freon to "new" freon, and there being a compatibility issue?

Just curious, because I heard some of that talk a few years ago when I was researching replacement cost for my outside heat pump / ac unit.

The current system was installed in 2003 and uses R-22, which will no longer be available after 2020.

The freon that replaces R-22 is R-410a, and moving to R-410a would require that both halves of a split system (outdoor condenser/compressor unit and indoor evaporator coil) be replaced.

I don't plan on owning the property more than a couple of years so replacing the existing R-22 condenser is fine with me.

What I'm finding is that there is an incredible markup on HVAC equipment which has created somewhat of a cottage industry on Craigslist of licensed HVAC techs who sell equipment directly on the side at steep discounts and offer installation.

I've had several bids come in now to replace the outdoor condensing unit, all of them $1500 or below from licensed HVAC techs who post on Craigslist, compared to the $3000 bid from the service company.

 

[DeborahB]

The current system was installed in 2003 and uses R-22, which will no longer be available after 2020.

The freon that replaces R-22 is R-410a, and moving to R-410a would require that both halves of a split system (outdoor condenser/compressor unit and indoor evaporator coil) be replaced.

I don't plan on owning the property more than a couple of years so replacing the existing R-22 condenser is fine with me.

What I'm finding is that there is an incredible markup on HVAC equipment which has created somewhat of a cottage industry on Craigslist of licensed HVAC techs who sell equipment directly on the side at steep discounts and offer installation.

I've had several bids come in now to replace the outdoor condensing unit, all of them $1500 or below from licensed HVAC techs who post on Craigslist, compared to the $3000 bid from the service company.

Sounds like things are looking up!

 

[Telly]

After January of 2010, it was illegal to sell systems that used R-22 in the USA. But replacement R-22 compatible condensing units and evaporators are still available, they are just charged with dry Nitrogen when shipped. The dry nitrogen is purged and the system is evacuated with the vacuum pump prior to charging with R-22.

R-410a is a totally different animal. It is an azeotrope, which brings a whole 'nother set of problems when determining system charge after a leak, and charging. It also runs at significantly higher pressures, and requires a different gauge set and hoses, etc.

And yes, for a while AC places were trying to push people into replacing the total system, saying they needed a new system "with the new freon" rather than just replacing the R-22 condensing unit if that was all that was really needed.