Issue:
Reset Relay Troubleshooting(R410A)
Resolution:
Refer to the preso slides below for visual aid of control voltage flow. The preso is available for download at the bottom of the article.
How It Works:
The reset relay is designed to energize upon a trip of any of the safeties/components within the circuit. The relay coil is in parallel with the safeties and in series with the contactor coil. Due to its high impedance value the relay energizes when a safety trips. The 1DL8 (or 1DL9 on two circuit units) is a 0.3-second time delay in series with the cooling relay contacts. The purpose of this relay is to prevent a condition known as "relay race" from occurring.
The below table indicates specifications of the safeties within the reset relay circuit.
Reset Relay Circuit Components
|
Component |
Specifications |
|
Low Pressure Timer |
10 Minutes |
|
High Pressure Cutout |
Make 550 psi / Break 650 psi |
|
Low Pressure Cutout |
EVPB: Make 105 psi/ Break 82 psi All others: Make 78 psi/ Break 58 psi |
|
Compressor Protection Switch |
Make 22 psi/ Break 7 psi |
|
Discharge Line Thermostat |
Make 180 F/ Break 230 F |
|
Compressor Circuit Breaker |
Refer to Service & Maintenance Section in IOM |
To properly define the cause of nuisance lockouts, the following steps should be taken.
1. Fuses should be installed across the contacts of the various controls in the reset circuit. To do this, an automotive in-line fuse holder assembly should be connected. Use 1/16A fuses. When one of the contacts in the reset circuit opens, the fuse will be required to carry the load of the devices downstream of the reset circuit. This will cause the fuse to blow. This allows visual confirmation and accurate data as to the device causing nuisance lockouts.
R410A - Tube and Fin Coil
Note: R410A units utilize a discharge line thermostat instead of a compressor winding thermostat. 80 - 120T units have utilize compressor protection modules. See Microchannel coil schematic to reference wiring.
R410A - Microchannel Coil
Note: 20 - 60T RAUJ units do not have Compressor Protection Modules
Note: Troubleshooting may require using more fuses than are shown.
2. If a "relay race" situation is suspected, try replacing the 1DL8 (or 1DL9 on two circuit units) with a known good time delay.
3. If momentary power interruptions are suspected to be causing nuisance lockouts, a special control voltage signal relay or a phase monitor may be required.
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.