AC won't start

[Friend of Pyewacket]

I have a 3 yr old Carrier 38TDB two-stage, two-zone AC system.

It worked fine in the fall but the AC won't engage when I call for cooling from the thermostat.

Is there some sort of fuse or reset I should check? Or anything of a homeowner diagnostic nature I could try?

[The local Carrier service company has told us that they cannot check refrigerant charge until the temp is well into the 80s. Apparently it's an added feature of the energy savings, two-stage compressor.]

[Samurai Appliance Repair Man]

If the compressor is not coming on at all -- sounds like that might be what's happening with yours -- then the first thing to check is the thermostat. A common failure in these A/C units is for the thermostat to fail open and therefore the compressor never comes on. You can test this by removing power and opening the control panel, get to the back of the thermostat and place a heavy gauge jumper wire across the terminals. Plug back in and fire it up. If the compressor comes on, order you a thermostat.

[Friend of Pyewacket]

The compressor was not turing on.

I called an authorized Carrier dealer. The tech added ~6 lbs of R-410A and it appears to be running OK. If history is any indicator, the AC should run though the cooling season and lose coolant over the winter.

Do you know if the change in refrigerant composition that results from the faster effusion of R32 would affect the performance of the condenser? [in a slow leak that occurs over the winter, the gas mixture in the condenser would become enriched in R125. My undergraduate physical chemistry text suggests the larger mole fraction (70%) and smaller molar mass (52 g/mol) favors effusion of the R32 over that of R125 (120 g/mol) in the R-410A zoetrope.]

[Samurai Appliance Repair Man]

[user=7707]Friend of Pyewacket[/user] wrote:

The compressor was not turing on.

I called an authorized Carrier dealer. The tech added ~6 lbs of R-410A and it appears to be running OK.

This problem and solution do not connect. If the compressor was not coming on, then this is not at all an indication that the system needs more freon! I fear you were the victim of a freon-adding monkey.

[Jedi Appliance Guy]

The Force has sent me a vision of It being off on the low pressure switch oh Wise One.  If there is a Puron leak we will know pretty soon.  I hope the Carrier Guy closed those service valves good n tight.

Friend of Pyewacket,  You may be the one who can explain to me how freon that falls to the ground like a rock cause it is heavier than air can somehow turn into carbon and/or chlorine and go high up into the sky and deplete ozone.

[Samurai Appliance Repair Man]

[user=2]Jedi Appliance Guy[/user] wrote:

The Force has sent me a vision of It being off on the low pressure switch oh Wise One. 

Good vision!

[Friend of Pyewacket]

Samurai -

Sorry, I omitted the diagnostic info from the air conditioner PCB.

The fault code light was signaling "low pressure switch trip." This info prompted the service tech to attach his pressure gauges and then top-off the refrigerant.

The Carrier service manual indicates there is protection "to prevent system operation if the pressures get excessively high or low. The air conditioner low pressure switch in the suction line opens at 50 PSI and closes at 95 PSI."

*******

Jedi -

You're asking about a lot of chemistry! Here goes:

Individual gas molecules are pretty zippy and will eventually diffuse into the upper atmosphere. There's an approximation from the Ideal Gas Law that says typical speeds for gas molecules are in the hundreds of mi/hr range. [http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/kintem.html#c4]

I'm under the impression that the two components of Puron, R125 (CHF2CF3) and R32 (CH2F2), do not contribute to ozone depletion since they do not contain chlorine atoms. That's not the case for R22 (CHF2Cl).

[Jedi Appliance Guy]

[user=7707]Friend of Pyewacket[/user] wrote:

I'm under the impression that the two components of Puron, R125 (CHF2CF3) and R32 (CH2F2), do not contribute to ozone depletion since they do not contain chlorine atoms. That's not the case for R22 (CHF2Cl).

I too am under the impression that is is the chlorine that depletes ozone.  But how can this be?  Every drop the pool guy pours into a pool evaporates does it not?  How do municipalities purify their water?  But there is no ban on chlorine.  And where did all these excess chlorine atoms come from?  Were they dumped on our planet from somewhere else or have they always been here from the beginning?

I thank you Friend of Pyewacket for your thoughtful and informative answers.  I am not attempting to debate you or put you on the spot. It's just that I have meditated,  I have contemplated,  I have stared into the bubbling acrylic cylinder of enlightenment,  I have been at one with the Force, yet I still cannot understand why there is no ban on chlorine if it is chlorine atoms that deplete ozone.