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Gas Absorption CU Fans

Yahoo Message Number: 85038
The design of the GACU is an evolving process. The first GACU I installed, had no provisions for mounting the fans. As such the Norcold OEM brackets had to be reversed to allow the twin fans to be attached to one of the absorber coils. Air flow is in the up direction to follow natural convective currents. The thermostat was mounted on one of the condenser fins exactly like the OEM setup. I noticed a bit more fan noise after installing the first Pines RV Refrigeration GACU. This is not coming from air noise but sympathetic vibration between the two fans. Slight variations is their speed causes additive and subtractive vibrations kind of like a motor boating sound. This vibration transmits into the Norcold refrigerator body and can rattle things in the frig box.
http://muniac.smugmug.com/Maintenance/Bus-Repairs/i-JDzzFcx/0/M/IMG_1177-M.jpg 1st GACU with fans mounted on left absorber coil.

As some here may remember, my original GACU replacement melted down owing to a fluke welding fracture on the heater pockets. The 2nd GACU I installed had a JC Refrigeration sticker on the absorber vessel. This GACU was designed slightly differently. First, there was a dedicated mounting place for the fans. Second, the fan thermostat had been moved.
http://muniac.smugmug.com/Maintenance/Another-Frig-Melt-Down-1142012/i-npmJsBN/0/M/IMG_3682-M.jpg Dedicated fan mounting area.

http://muniac.smugmug.com/Maintenance/Another-Frig-Melt-Down-1142012/i-dTsBB7b/0/M/IMG_3681-M.jpg New fan thermostat location.

As I am told, the new fan thermostat position results in more efficient operation. I've observed this as more frequent shorter cycles. In my case the noise levels went down with the new fan location. I can only hear the fans run if I put my ear on the side of the frig. The detailed observer will note one fan comes close to a tubing run in the second GACU. I had to make sure there was no contact here. If a fan is touching something this could result in louder operation. Something to pay attention to when doing the repair. I'd also add there is much more to doing a proper repair than a quick in and out of the GACU.

Expulsion of heat is important. It can be accomplished by increasing the radiating area. (Note cheap Norcold OEM has one absorber coil versus two on the quality JC GACU.) And by forcing air. Or both.
Fans also add another component to the system, introduce noise and dust. I've also been told that the twin absorber coil system doesn't require fans. This would make sense since a goodly amount of the GACUs are used in Amish residences without electricity. I like fans and forced air cooling so I installed mine. As of this moment, everything is working within expected parameters.
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Best - Scott

2006 Allure 430 40' #31349

(Bus-Stead Lemon) My Allure Page http://www.muniac.com/Allure%20Page.html