Armstrong HP not cooling well

[machineman32]

Recently had a warm day in PA around 88 deg low humidity inside temp 86 deg set therm at 72 HP ran about 2hrs and temp only 79 supply temp at register was 74. Went outside air exiting top of HP was approx. same as outside air temp. My second HP (I have two separate systems both same model) had much warmer air exiting unit. HP are 6yrs old. Had Tech out to take a look and his recommendation is to perform a full leak check. Would like to know if Tech is heading in the right direction. Here is his notes fan amps.6 comp amps 3.6 supply temp 45 deg return temp 62 deg (checked near air handler) supply 48 deg at register farthest away.(temps were checked shortly after unit was turned on approx 15 min.) Suction pressure started at 65 and after running maybe 30 min dropped to 36. Thanks in advance for any help.

[beenthere]

usually, a unit low on charge doesn't take long to drop pressure like that. Could be a problem other then leaking and low on charge.

[machineman32]

Had another company out for a second opinion first visit tech checked unit out said it was working correctly couple days later back to not cooling again gave same tech call and this time found low pressures. He added a small amount of freon and told me pressures didn't change and was sure there wasn't a leak and that the indoor unit tx valve may be bad.Does this diagnosis make more sense than the first?

[XcelTech]

I am confused.

Tech #1 shows up and the unit is not cooling. He checks the system and says it has 45° air exiting the register and a return temp lower then the Thermostats setpoint? He suggested a leak check. A return temp lower then the setpoint is one issue, but what did he do that caused the system to start working again? Did he do anything?

Tech #2 shows up while the unit is working. He can't find a problem and leaves. On his second visit the unit is not working, he adds refrigerant to get the system to cool the area. He says there is no leak but had to add refrigerant. He says it is a TXV issue because adding refrigerant didn't change the pressures and that means there is no leaks. I wouldn't use that guy again unless you are missing some pretty important information.

I would say there is alot of information missing here. I am sorry but at this time I cannot give you a good evaluation of the work these techs have preformed.

I would suggest checking the AOP Contractor Map for a company in your area and getting a third opinion. I would suggest asking three basic questions.

#1 - Explain the problem, why it is a problem, and the steps to repair it.
#2 - Explain the evidence that has lead to this conclusion.
#3 - Explain how the test were preformed to get this evidence.

[BaldLoonie]

Suction dropping like it did sounds like bad TXV to me.

[crymtide]

Or suction dropping like it did could be refrigerant beginning to pool in evap as it starts to freeze up from low refrigerant levels, or metering device issues, or air flow issues, or other things I would think to check as I eliminated others. the bottom line is pick a pro call the pro tell him what's been going on, and let him alone while he comes up with a solid diagnosis. Multiple opinions have multiple diagnostic fees, and no we [hvac techs] are not perfect, not all honest, not all thorough, any more than plumbers, car mechanics, teachers, cops, or anybody else. When you find a good one; stick with him/her and still don't expect perfection every time. I wish you the best of luck.

[machineman32]

To clear any confusion when tech #1 checked pressures they were okay at first but after about 45mins they dropped and the split between supply and return was maybe 7 degs. He made no repairs and told me to call office and set up time for leak check..... didn't run A/C for a few weeks. Last week tried using A/C again and wasn't cooling called Tech #2 different Company first visit found pressures to be correct. Tech #2 second visit checked pressures and found them to be low he told me he added a small amount of freon and pressure did not change which led him to believe no leak and a possible faulty txv that was late in the day Friday and he wanted to contact Armstrong tech support this coming week. I have noticed the unit briefly cooling but not for long.Also I have checked the AOP map but none listed nearby hour plus away.

[crymtide]

Just for me a guy who adds a little refrigerant to see what happens is not following a correct diagnostic path and shouldn't be called back.

[XcelTech]

Tech #2 could be right. I still am not impressed with adding refrigerant and saying there is no leak. I don't know why you would need to add refrigerant to find or diagnose a problem. If it is the TXV it should be freezing up near it. If its a LPS he should be able to take a multimeter to it to find out. Having a 48°F coming out of the supply makes me feel like it is not a TXV issue.

I am leaning more towards an air flow issue. 48°F is lower then what I would expect to get out of a well working system. However, if the fan speed was way lower then it should be it would allow for a colder air temp. A lower fan speed or air blockage would account for a slow mild freeze up that would cause a blockage that would intern stop the unit from running if it has a LPS. This would also cause intermittent issues, short cycling, and be hard to diagnose with a 10 min service call just checking pressures outside.

The best way to figure this out would be to find out what the amps of the evaporator fan are suppose to be and measure what they are.

Has either of these techs gotten into your attic and checked the fan or coil?

[machineman32]

Yes both techs have checked air handler, coil+filter is clean I did see tech #2 move what I believe is the bulb to the txv outside of the air handler with the covers installed and ran HP in cooling and heat mode while checking something outside then put bulb back in place before he left.

[machineman32]

Update, tech #2 replaced indoor TXV on friday ran a/c all weekend works great.

[BaldLoonie]

Junior boss's sweetie had a unit that kept going on on low pressure lockout. But all looked good everytime we checked. So I parked a tech out at the unit for 2 hours, sure enough, the TXV finally shut down just like this one.