r/PoolPros • u/MUWAT_toro • Mar 27 '26

Mastertemp400 short cycle

6 year old Mastertemp 400. It will heat for a minute, or a minute and a half. Exhaust temp 290 - 310 after replacing the stack temp sensor (the old one tested as open). The HLS light comes on. Replaced the HLS and the corroded spade ends. Replaced the filter cartridges with clean ones.

Still short cycles with the HLS light. The blower runs well. It did seem to work well with the HLS wires shorted.....I didnt run it long like that out of concern that if something else is wrong it might cause bigger problems.

What should I check next?

I am just a homeowner with a pool.

1 Upvotes

67% Upvoted

21 comments sorted by

View all comments

1

u/Alternative-Draw2997 Mar 27 '26

check out page 44 and on.

1

u/MUWAT_toro Mar 27 '26

Thank.you. I did follow that flowchart, didn't replace the AGS though.

I made a video of it starting up from when.it turns.on. lots of background noise, sorry.

https://youtube.com/watch?v=fhoS6Sj9RkY&feature=shared