Hello again I have seen heat pumps last 20+ years...its not common however. And will not generally warrant more than minor repairs.
The newer ones have deceptive warranties, the long lasting compressors are guaranteed for 10 years....but you can spend a thousand dollars or more keeping it running until then. Average life span is about 15 years... many are worn out at 10 years. Depends on the quality of the installation and other factors.
Tell me if the fan on the outside unit stops when the compressor stops running and the suction line goes warm or not. If the fan keeps running and the compressor stops, the compressor is going off on its internal overload in most cases. If both the fan and compressor stop the unit could be going off on its high pressure safety cut off switch.
The fan continues to run after the compressor stops (and the suction line begins to warm).
*** The compressor is over heating, most likely due to dirty or fins clogged with salt water corrosion deep between the fins.... less likely because of other reasons.
let me know about those issues.
Tell me when the unit was last worked on... there is a chance in that case that the system was over charged by a few ounces of refrigerant in that case.
The unit was last worked on August of 2012. At that time the tech said the gas was perfect and did not need to be charged. He measured suction pressure at 56 psi and head at 225 psi (). The anti-corrosion spray was applied as suggested earlier.
**** You have an honest and capable repair man on your hands...don't loose his card. feed him a sandwich next time he comes by. Those pressure readings are close to ideal especially if the condensing unit is more than 50 feet away from the indoor unit. (ideal is 60 psig if unit and the cooling coil are within 15 feet) His gages could have been off by 2 psig as well.
The suction pressure would also be low because the cooling coil inside is partially clogged up, no doubt about that after 12 years, the blower vanes also pack with dirt in that time span... those should be cleaned as well. your service people will charge you about $250 for that.
This problem has been intermittent since May of 2011. In 2011 a tech visited as well. Anti-corrosion spray was applied but I can’t find the service sheet to tell me the other details.
And... tell me what your monthly electricity bill is in the summer as compared to the winter... from that I can assess the viability of changing out the cooling part of the system to a much more efficient system than was commonly available in 2011
In 2001... Regardless, I’m not too worried about the cost of cooling. Our hot season is short (about 2 months) so the total cost of cooling is not that significant. My electricity bill for the year is $3200.
****Thats not out of line for a medium to larger size home.
There will be a SEER rating stamped on the name plate of that unit... see if you can find it and tell me what it says. If the SEER rating is 12 or less, you can probably reduce your cooling costs by 40 to 50% per year. making the current unit even less viable to repair.
The SEER is 14.05. HSPF is 8.4 and is more important in my climate - I see newer units are up to about 25% more efficient.
*** Thats pretty good efficiency...a new unit would take a bit too long to pay off on energy savings alone.... lets hope its just a clogged condenser coil.
a new unit can also be bought with coils not subject to salt air corrosion, or coated at the factory.
That would be nice!
** there are two options along those lines, copper tube and copper or cu pro-nickel fins (drives the cost up by a few thousand dollars and may not pay off in your only semi corrosive environment).... and 'epoxy coated coils) which add a few hundred dollars and will be a good investment in your case.)
*****Before you spend money on replacement though have the coil completed cleaned with inhibited acids down to bare metal...and checked out as I mentioned in my earlier post... watch the work being done yourself so you know what to look for.
Let me know what pressure and corresponding temperature reads they get... pressure reads without corresponding temperature reads, mean very little.