Honeywell CECOMINOD032202 FBA C7735A1000, Gray

This is an easy DIY fix. I saved a few hundred bucks too avoiding an overpriced HVAC service call. My issue was the three thermostats on my 3-year old multi-zoned AC system were all calling for cool air but the compressor was not turning on. The problem, it turns out, was not the typical start capacitor or contactor failure, as online professionals explained those are the typical problems. (Those parts are also an easy test, by the way, using a Fluke 117 or similar multimeter and some simple diagnostic steps. They are also DIY-friendly to replace if you follow appropriate electrical precautions). In reality, there was no 24V signal to turn ON the compressor. It turns out my Honeywell 3-zone controller (HZ311) was flashing its green COOL light instead of holding steady ON, thus preventing delivery of the 24V ON signal to the contactor. One look at the HZ311 manual quickly revealed the answer. The controller thought the duct temperature was below 45F, falsely thinking the system was overcooled. That temp was impossible since the compressor had been off for a day. Remember this - systems are designed to shutdown when sensors fail, before something irreversible happens. I now suspected that this DATS (duct air temp sensor) failed. I tested this by disconnecting one wire of the suspect DATS from the controller. My compressor kicked on immediately and AC resumed. The compressor turned off later when the goal temp was reached. I immediately ordered this part. A few days later when it arrived I installed it and my system continued to work flawlessly. No more false 45F degree duct temperature reading. I did measure and compare resistance of the old and replacement sensors and found a huge difference. The old sensor reported about 300x the resistance of the new sensor. It read over 3 megaohms.

5 out of 5 stars - this little sensor saved my summer! To be honest, I don't really care much about the technical specifications or fancy features of this temperature sensor. What I care about is that it solved a serious problem that was driving me crazy. My home's HVAC system had a faulty temperature sensor that was sending incorrect signals to the control board. This caused my air conditioning to barely function - it would start cooling for about 90 seconds, then automatically shut off for over 20 minutes, creating this endless frustrating cycle. My house was unbearably hot and I was getting desperate. After extensive troubleshooting (and probably too much time on Google), I finally pinpointed the problem to the temperature sensor. Once I replaced the old broken one with this unit, everything started working perfectly again. No more constant cycling, no more interrupted cooling - just reliable, consistent air conditioning like it should be. The installation was straightforward, and the sensor fits perfectly in my HVAC system. It's been running flawlessly for weeks now. If you're dealing with similar HVAC issues where your system keeps cycling on and off, this might be your solution. Sometimes it's the simple, inexpensive parts that make all the difference. Highly recommended!

Did the job. Top Quality. Best Price

Product works perfectly and was a breeze to install. HVAC technicians in my area quoted me $120+ to replace. It took longer to get up into the attic than to replace this sensor. It is held in by 2 screws and uses 2 wire nuts. This is essentially a resistor in a metal tube with a fancy plastic top. There is no polarity to the wires so you dont need to worry about messing that up. Installed and verified working in under 5 minutes. Saved me $80+.

10 year old system…HZ311 Zone controller, Carrier Furnace/AC. Both the heat and A/C would “short cycle”. The cool light on the zone controller would flash for a few minutes then kick the A/C or heat back on for a few minutes. Took forever to heat/cool the house needless to say. Researched the error code of the flashing light on the Honeywell website. Traced the issue back to this sensor. Knowing what an HVAC repairman charges to do the simplest of tasks, the $30 risk was minimal to pay someone to come look at it. Reading other reviews there’s guarantee even the professional would be able to fix it. Took less than 5 minutes with 1/4 socket and good as new.