ICM253 Adjustable Fan Delay Timer | Post-Purge Off Delay Control | 12–390 Second Adjustable Delay | 18–30 VAC | UL Recognized HVAC Blower Fan Control Board for Efficiency & Comfort

It's a very useful device. It allows me to make the fan on the central air continue running for a short while after the compressor ends its cycle; otherwise, they both stop when the thermostat setpoint is reached. The range for the delay is anywhere from 12 to 390 seconds. Anecdotally, I have already seemed to have found that it reduces the loss of cool temperature into the encapsulated crawl space. Now I just need to determine how long to run to purge the conditioned air through the system.

As others have said, the schematic printed on the relay is wrong! The accompanying piece of paper is correct. Pins 2 & 3 require a constant 24VAC. With pin 2 being the red wire and pin 3 the black (common). You connect the green (fan) wire from the thermostat to pin 4. Connect pin 1 to your fan relay. When the relay receives a signal from the thermostat on pin 4, it connects pins 1 & 2 together. The relay says it will do a delay of 12-390 seconds. This is wrong. The shortest delay (the dial pointing at 12) is 2 minutes and 56 seconds. I have left it connected with the 3-minute delay. It seems to be working okay.

Works as intended--the fan still runs ON SELECTED TIME after the condenser turned off from outside. I set mine to about 2 minutes after the thermostat cuts off the A/C. Installation: Like the diagram on the ICM253 unit. --1 and 4--bypass (undo and reconnect) the current GREEN wire from the Fan (1) and the GREEN wire from the thermostat (4) --2 and 3--tap (add into existing) into the 24vac from the RED (2) and BLUE/common/neutral (3) wires I did not see the BLUE/COMMON/NEUTRAL 24vac wire once the furnace was opened. The wire diagram makes no sense at all !!! Google and YouTube did not help. So I removed the two screws and take out the cover that protected/covered the wirings and the 24v transformer (besides the breakers). I look for the 24v transformer and its Common/Neutral wire---It has wires out for the 24vac and wires in from the 240vac (labeled on the transformer...see picture). I saw the 24vac Common/Neutral wire (gray colored on this wire). I also saw that it was connected to the condenser outside...I simply tapped into that gray colored wire and done. Hope it helps someone out a bit. Have a great day.

Delay on break 24v relay timer . Installed on signal side of Hvac blower relay to trick the relay into thinking the Wall Thermostat was still outputting “ Blower ON “ signal keeping the blower running after the Thermostat has already turned off the blower relay Basically turns your regular Blower Relay into a time delayed solid state relay . They call it delay on break ( so when Wall thermostat switches off this timer sees the “ break “ & then applies constant voltage back to the blower relay mimicking “ ON “ signal from Wall thermostat ) Follow downloadable manual instruction PDF for this model delay timer ( follow diagram exactly ) If wired correctly your splicing it into the 24v Transformer in the Hvac Air handler so it can mimic the 24v signal from the Wall Thermostat when turned off ( for the exact time you’ve got the delay set on with the knob ) Used this to leave the Blower running 30 seconds after the unit is signaled off from Thermostat so the Heat Elements could cool off before blower turns off There are Wall Thermostats out there like Honeywell Pro WiFi @ Zwave that have this feature under “ Advanced Setup “ menu , but there 5x’s the price of this

I installed the ICM253 Fan Delay Timer to help with short cycling on my HVAC system, and it does exactly what it’s supposed to. The delay function helps the fan run a bit longer after shutdown, improving efficiency and airflow. Installation was fairly straightforward, but I’d recommend double-checking the wiring instructions—it’s easy to mix up connections if you’re not careful. Once set up, though, it works flawlessly. Overall, a solid upgrade for HVAC efficiency, just take your time with installation!

I have two air-conditioning zones in My Home and the upstairs unit has a built-in delay timer in the control board. The downstairs unit never had the delay feature and this was an easy modification. I only set it for 55 seconds fan run time after the condenser shuts off And this extracts quite a bit of cooling without rehumidfying the space. Without the timer duct temperature is 52° when the fan shuts off and with the timer it’s 60°

Mine didn't work, and being's I waited till this spring to install, the warranty had expired. I thought it was year but it's only a month. Ordered another, which is working fine.

My air conditioner was "freezing up" -- that is, over time a huge block of ice would form on the evaporator coil, eventually blocking all air flow. Service technicians couldn't figure it out: had proper amount of refrigerant, blower fan was on highest speed, ductwork was clear and properly sized, filter was clear, unit was proper size for the condo. Eventually I decided that it was the 200 feet of pipe between the condenser and evaporator. When the thermostat called for the AC to stop, the compressor and blower would stop at the same time, but you could hear refrigerant hissing through the pipes for another 90 seconds or so (because the pipes were so long, it took a while for all the pressure to equalize). so I figured evaporator would get too cold during that time since the fan had stopped. So I installed this delay-on-break switch to make the fan run for another 90 seconds after the compressor stopped. I verified with an infrared temp sensor that the evaporator coil returns back up to room temperature before the fan stops, so no ice buildup. In the year since I installed it, there hasn't been a single occurrence. Problem solved!