Issue:
Shell and Tube CGAF Chiller trips on High pressure
Resolution:
CGAF - Shell and Tube
CGAF with only 2 fan outputs.
If the chiller is a low ambient chiller, and there is a possibility that another tech has been working on this product, there is always the possibility that some components could have been replaced in the control panel.
Indication:
One possible indication of this is that when the chiller starts and then commands the fans to start, the fans will start normally but when the head pressure begins to drop and is under control, BOTH fans will stage OFF. This will result in excessive head pressure and an eventual chiller trip. If this occurs, a quick check of the control panel can reveal if the dual SCMs (1U49 single, dual) have been replaced by a single MCM. If this is the case, there could possibly be a software mismatch between the CGM (1U48) module and the newer MCM (1U49) module. To effectively remedy this, change the CGM module to a more recent version. The CGM replacement in CATS will have the newer software installed.
Wiring:
Once the new modules are installed, the fan output and fan wiring must be changed on the modules to take advantage of the additional fan output found on the newer MCM. The "as built" fan connection wiring shown in the early models' schematic does not show the "Low ambient cond fan" connection (J26-5,7) circuit #1 and similarly on circuit #2 (J26-1,3), these are found in current and later models' schematics.
Simply connect the fan contactor (1K7) wiring to the J26-5,7 ckt 1 and J26-1,3 ckt 2 and the fans should work and maintain head pressure
Notes:
- SCM=Scroll Compressor Module
- MCM= Multiple Compressor Module
- CGM=Cold Generator Module
Changes:
Other Question/Problem/Cause Statements:
- Why do my condenser fans shut off at the same time?
- Should I have at least one fan on when a compressor is running?
- Replaced SCM with an MCM but my chiller keeps tripping on HPCO
- Will an SCM that was replaced by an MCM cause problems with my head pressure?
- I have a low ambient chiller but my low ambient fan does not run.
- My chiller schematic does not show the "Low ambient Fan" output.
- Can I upgrade to the MCM on my SCM equipped chiller?
Facts:
- Air-Cooled Chiller - Intellipak (CGAF)
Document Identifier: DOC-93137
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.