Run cap going bad 3 in 6 weeks.

[mcewans]

Hey all,

Had a call today a Trane XL12 4 ton split system from 1/2001. Dont have model or serial handy. Anyways about a month ago a tech went out and did a C&C and found run capacitor low on MFD's. Cap is a 50/7.5 440VAC. He changed it out only had a universal cap for that size. Cap work and unit ran for 3 weeks.

Another tech got called back out, cap bad again. Figured maybe fault universal cap. Replaced again with another univeral. Worked for 2 1/2 week.

I got the call today and sure enough cap was bad again. So I replaced again mean while I checked amp draw on the compressor. RLA 16.0, compressor running at 10A. Pressures were good, 10SC and 18SH TXV system. Condenser fan RLA 1.9A, fan running 1.6A.. Check voltage of each leg out of contactor 248VAC. 123VAC and 125VAC on each leg to ground.

Any idea what could be causing cap to blow? All connections tight... Thinking power issue supplying unit, customer has another unit the same and it has had zero issues. Ordered an OEM cap to try also will put it in tomorrow.

Any ideas?

PS, Cap is a motor-mate universal

Did the compressor part of the capacitor go bad or the condenser fan motor part? If it is the same part of the capacitor each time it goes bad, then I would look elsewhere for a problem.

[ar_hvac_man]

Pretty sure those have non-bleed txv's and require a hefty start capacitor. Did it test ok?

[Glennhvac]

I have had sitiuations like this. after 3 caps I found that the compressor terminals were dirty. cleaned terminals crimped on new stakons, after that no more problems. ckeck for tight connections at the comp.

Nice idea. Note to manufacturers: Can you design units again so that we can in fact check the freaking terminals without using a mirror and flashlight! Yeah, it's a fed up with it rant.

[skidoox800]

Both sides of cap bad. Herm and fan. Going to try oen cap. Talk to supplier thos morning they stopped selling those caps because all the failures they were getting back. Warranty cap with a turbo 200. Only universal cap I'll use. Emergency only.

[chuckcrj]

What was the voltage between the start and run winding?

[catmanacman]

Pretty sure those have non-bleed txv's and require a hefty start capacitor. Did it test ok?

I think your on to something