Reading Sensors... HVAC Error

[aShop]

My heatpump stopped cooling the other day. I popped the cover of the main switch (sorry I am not sure what the name of it is) and I can manually press it and everything works fine. So I assume there is something off with the main board. Some of the resistors look like they got warm but I don't see any major burn marks on the board. I can hear it switch over when going from heat to cool. The thermostat just says reading sensors... Do you guys have any advice?

 

[bonneyman]

That "browning" of the board is typical for boards with resistors like that. They do get hot, but - as long as the color bands on the resistor are undamaged - it's probably not excessively hot for them. Depending on the orientation of the board, any microchips or diodes above that row of resistors could get damaged by all that heat though.

The board could probably be bypassed to allow for cooling operation, but you'd have to know some technical stuff. I've done it before so the customer could have cooling while I secured the parts needed to fix it but I wouldn't recommend a DIY do it.

 

[aShop]

The board could probably be bypassed

That is exactly what I have been doing for the past couple days.

 

[pcmeiners]

One of the most important item to get for any minisplit (any machine) is ALL the manuals, most important is the technical/engineering/trouble shooting manuals. See if you can find them on the web. Sensors are all going to be thermistors

 

[bonneyman]

That is exactly what I have been doing for the past couple days.

Cool! That gives you some breathing space.

If the sensors are thermistors many times they are soldered directly to the board. So, if a thermistor goes bad, the whole board has to be changed, as all the pieces are calibrated together at the factory. Another "benefit" of our all electronic control mania.

 

[Wrench97]

Does it have high or low pressure sensors on the unit?
Any flashing LEDs anywhere?

 

[fitter30]

When a failure happens like a sensor either it shows up on a indoor unit by a number or flashing lite count on the board in the condenser. Sensors can be ohmed out disconnected from the board by a plug.

 

[pcmeiners]

"If the sensors are thermistors many times they are soldered directly to the board. So, if a thermistor goes bad, the whole board has to be changed,...."

Minsplits have multiple thermistors. If a thermistor goes bad, a replacement with one of the exact specs is all that is needed, no calibration is needed.

 

[fitter30]

Brand and model of the condenser? Board number?

 

[Wrench97]

Is this a Honeywell tstat with remote outdoor sensors?

 

[aShop]

Is this a Honeywell tstat with remote outdoor sensors?

Ha yeah. Now that you say that I realized what the message is.

OK so to answer the others, there are no flashing lights on anything.