Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: 18360 on February 01, 2021, 04:42:53 pm

Title: Rooftop ac
Post by: 18360 on February 01, 2021, 04:42:53 pm
Does the front rooftop unit typically put out a little higher temperature of airflow than the rear unit.
It seems like it is colder back there, than in the front.  Could it be the larger sq footage in the front?

Thanks
Title: Re: Rooftop ac
Post by: Chuck & Jeannie on February 01, 2021, 04:46:11 pm
When we run both units set to the same temp, it is always colder in the bedroom, and that unit runs less often.

Like you said, smaller area to cool seems the likely reason (assuming both units are the same size/model).
Title: Re: Rooftop ac
Post by: Pierce & Gaylie Stewart on February 01, 2021, 05:02:31 pm
Check the outputs with an inexpensive IR gun.

Pierce
Title: Re: Rooftop ac
Post by: Elliott on February 01, 2021, 05:42:42 pm
You front AC is also closer to the front door and near bigger windows, so all things being equal, it'll probably be the first one to "plug up". If Pierce's recommendation does confirm that the front is not as cold, I'd hop up there with a can of cleaner and spray the coils/fins. I'm going to be doing mine soon with this: Amazon.com: Frost King ACF19 Foam Coil Cleaner, 19Oz, 19 Ounce: Home Improvement (https://www.amazon.com/gp/product/B007I7KZN0)
Title: Re: Rooftop ac
Post by: Pierce & Gaylie Stewart on February 01, 2021, 07:13:47 pm
I'm never sure which position is recirculate on our window air so I tried both with the gun. I got the idea pushing the recirculate button in the car and checking temps.

The output temp of the AC changes as the TEV opens (A thermal expansion valve or thermostatic expansion valve (often abbreviated as TEV, TXV, or TX valve) is a component in refrigeration and air conditioning systems that controls the amount of refrigerant released into the evaporator and is intended to regulate the superheat of the vapor leaving the evaporator.) so the temp can change as more refrigerant is allowed into the evaporator.

For those new to AC, ice will form and block the evaporator unless a temperature controlled valve controls the amount of refrigerant allowed by the sensor in the fins on the evaporator.

Pierce
Title: Re: Rooftop ac
Post by: Realmccoy on February 02, 2021, 07:51:14 pm
I cleaned my evaporator and condenser coils on both AC units in November after watching a YouTube video. They did not operate properly afterwards. My mobile RV tech fixed in five minutes. The phone like control wires were either disturbed or got some cleaner in them. Unplug, shot of contact cleaner and replug. Everything worked fine after that. Lesson learned. 1998 Duotherm units with heat strips.
Title: Re: Rooftop ac
Post by: 18360 on February 08, 2021, 01:17:45 pm
I found someone to charge the front ac unit.  He tapped into two separate copper lines and added freon. 
So far it is working perfectly (very cold).  I will see how long it lasts. 
It only cost me $150 so it is worth a try.
Title: Re: Rooftop ac
Post by: wolfe10 on February 08, 2021, 01:21:46 pm
Since it is a sealed system, if you had to have it recharged, there WAS a leak.

Did they find/fix the leak?
Title: Re: Rooftop ac
Post by: 18360 on February 10, 2021, 01:48:15 pm
No just recharged.
He mentioned about a valve that was stuck.  I'm not sure what he meant.

Rick
Title: Re: Rooftop ac
Post by: Chuck & Jeannie on February 10, 2021, 03:23:47 pm
He mentioned about a valve that was stuck.  I'm not sure what he meant.
If air conditioner is a heat pump model, then he may have been referring to a stuck reversing valve, which could impact cooling performance.