GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Mitsubishi MXZ-5C42NA2 – defrost with no ice?!

m_sea | Posted in General Questions on

I am in Seattle, and have a 4 head Mitsubishi 5c42NA2  (6,9,12,15k FH heads) system. While the temperature output is fine, the defrost behavior of this unit is bizzare:

1. Main concern: Doing a defrost cycle with ZERO ice on the outdoor unit, not even a drop of water coming out by the end of a defrost cycle at 36 degrees, in low humidity conditions.
2. Defrosting at 45 degrees
3. One time when I got a few inches of snow, it froze solid and would not call for a defrost (lol) – had to put the unit into cooling mode for it to work

The techs once overcharged the unit to 11 lb 6 oz, then they removed all refrigerant and weighed it in again at around 8lb+ I believe. I have about 170 ft of lineset and ~30ish bends.

The techs also checked the resistance of a few thermistors – I don’t remember if they did them all, but the ones I saw them check, looked correct.

While I am learning to live with the awful diesel truck idling sound when the unit is heat mode, this whole defrosting with no ice nonsense is frustrating.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |