The new Carrier 27VPA9
This new unit is a noncommunicating variable 5 speed performance line heat pump with InteliSense technology, 19 seer2. Sizes range…
Author: Jonathon Pullen
Technical Services Manager
Gulf Coast District
Troubleshooting Codes 25-XX
Have you worked on the new 20, 21, and 23 SEER2 units and encountered a fault code 25-XX (for example,…
38MU/40MU Crossover System
In this article, I will explain how to wire the new crossover system for 24V communication or scenario 3 using…
Overheated Thermostat
Have you ever run across an overheating thermostat? Where the thermostat displayed 90 and the room temp was in the…
38MU/40MU 18/8 Low Voltage Wiring
This month, I will be covering how to properly wire a 38MU/40MU for 24V operations and setting up the DIP…
Late Friday Night
It’s late one Friday night and you are on a call with a bad OFM (outdoor fan motor). The OFM…
DUCKT-STRIP Wiring
DUCKT-STRIP wire is a great product for ductless units when used properly. The wire is used to power and communicate…
Adaptive Heat
If you have a 2-stage performance furnace, you have a heat mode called adaptive heat. Adaptive heat can be controlled…
Because I was Inverted
For this article, I will explain how to replace the main control board on a 38MARB ductless outdoor unit. The…
Does the Defrost Board Have 24VAC?
The heat pump works in heating and cooling mode but it simply will not go into defrost mode. Why won’t…