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Car Forum / Driving, Maintenance, Tuning / RVs / June 2005A/C doesn't cool very well
I've own a low mileage '84 Sportscoach Pathfinder. Everything works except that the roof A/C doesn't cool nearly as well as it should. I suspect the thing is gone low on freon over the years. I don't have any experience with RV air conditioning. Is there a way to check/recharge the system? I inquired about new unit prices and at $700.00 you can bet I want to try and fix the one I have! Thanks to anyone who can offer advice. > I've own a low mileage '84 Sportscoach Pathfinder. Everything works > except that the roof A/C doesn't cool nearly as well as it should. I [quoted text clipped - 5 lines] > > Thanks to anyone who can offer advice. The cooling system is a sealed unit using soldered copper tubing and R22 refrigerant - there are no hoses or fittings (the same type of system used in refrigerators and window ac units). While it is possible to have an appliance or commercial refrigeration technician solder on a service valve and check/adjust the charge, it's not going to be cheap - nor is it likely to be your problem. I'd first make sure that the condenser is clean and airflow through it isn't obstructed by crud or bent fins - then look at the airflow to and from the evaporator, making sure that all gaskets etc. are doing their job. Remember, warm air coming from the coach and cool air coming back from the evaporator all have to make their way through a 14x14 opening in the roof - if the two airstreams aren't completely separated, you'll lose cooling capacity. Use a thermometer to measure the air temperature coming back to the coach - it should be 30-40 degrees cooler than the air going to the evaporator. Alan > > I've own a low mileage '84 Sportscoach Pathfinder. Everything works > > except that the roof A/C doesn't cool nearly as well as it should. I [quoted text clipped - 21 lines] > coach - it should be 30-40 degrees cooler than the air going to the > evaporator. That must be one heck of a system to have a 30 to 40 degree temp difference! I've usually seen them at 17 to 21 degrees. Clean the condensor with detergent and a hose, then clean the evaporator coil with a brush . Measure your return and supply temps...should be near 20 f. after its run for about 5 minutes. Make sure the compressor isnt short cycling for some reason . IF the compressor is staying running the entire time and you have less substantially less than a 20 f drop , then, strongly suspect the Unit being low on charge. > Clean the condensor with detergent and a hose, then clean the evaporator > coil with a brush . Measure your return and supply temps...should be > near 20 f. after its run for about 5 minutes. Make sure the compressor > isnt short cycling for some reason . IF the compressor is staying > running the entire time and you have less substantially less than a 20 > f drop , then, strongly suspect the Unit being low on charge. And the pedophile is heard from again. 'And the pedophile is heard from again.' ME: More obvious rubbage . > 'And the pedophile is heard from again.' > > ME: More obvious rubbage . Dave, get a life. Everything you post , as well as what I post, is on the net somewhere. You said that once about wanting to diddle kids, don't deny it. >> > I've own a low mileage '84 Sportscoach Pathfinder. Everything works >> > except that the roof A/C doesn't cool nearly as well as it should. I [quoted text clipped - 26 lines] >That must be one heck of a system to have a 30 to 40 degree temp difference! >I've usually seen them at 17 to 21 degrees. When the outside temp is 85 degrees, the outlet temperature is 40 degrees. That's a 45 degree differential. Coleman 13500 BTU.  SignatureFrank Tabor > When the outside temp is 85 degrees, the outlet temperature is 40 > degrees. That's a 45 degree differential. Coleman 13500 BTU. I have one of these in my pop-up and I don't run it on high very much. It does a really good job of cooling. I guess that I will put it to the test in two weeks when I go camping in what will probably 90+F temperatures. 'When the outside temp is 85 degrees, the outlet temperature is 40 degrees. That's a 45 degree differential. Coleman 13500 BTU. SignatureFrank Tabor' Reply: Testing the A/C's effectiveness is done by seeing how much of a temp drop there is across the evaporator coil (inside coil of the a/c). 17-21 f. is considered good. This is the difference between the return air from inside the Coach and the discharge air right at the a/c unit. Also, if he were to look at the evaporator u bends on the ends of the evaporator coil and some were frosted...that would be yet another indication that the system is low on freon / malfunctioning. > 'When the outside temp is 85 degrees, the outlet temperature is 40 > degrees. That's a 45 degree differential. Coleman 13500 BTU. [quoted text clipped - 9 lines] > evaporator coil and some were frosted...that would be yet another > indication that the system is low on freon / malfunctioning. You're almost right, Pedophile. 'You're almost right, Pedophile.' ME: No...i am right, willful LowLife. > 'You're almost right, Pedophile.' > > ME: No...i am right, willful LowLife. Oh, so you're preaching to me? You got the wrong pulpit, Pedophile. You know, that's about the closest you've ever come to getting one right without repeating what someone else said. Dave, you uneducated fundy moron, you're about as welcome here as a turd in a swimming pool > >> > I've own a low mileage '84 Sportscoach Pathfinder. Everything works > >> > except that the roof A/C doesn't cool nearly as well as it should. I [quoted text clipped - 30 lines] > degrees. That's a 45 degree differential. Coleman 13500 BTU. > -- If you use that style of thinking, you're right. If you use linear thinking, it's wrong. You are supposed to measure the temps across each coil, the evaporator and the condenser. >> >> > I've own a low mileage '84 Sportscoach Pathfinder. Everything works >> >> > except that the roof A/C doesn't cool nearly as well as it should. I [quoted text clipped - 44 lines] >If you use linear thinking, it's wrong. You are supposed to measure the >temps across each coil, the evaporator and the condenser. You can't get to them on a RV AC unit, dickhead. SignatureFrank Tabor > >> >> > I've own a low mileage '84 Sportscoach Pathfinder. Everything works > >> >> > except that the roof A/C doesn't cool nearly as well as it should. I [quoted text clipped - 46 lines] > > You can't get to them on a RV AC unit, dickhead. Ohh, resorting to foul language? Does that make you feel like a big man now? Huh, little boy? Actually you can measure those temps easily. Find out where the return air is. That's where the air is returning to the evaporator. Measure that temp and write it down if you need to. Then find out where the air is blowing out. Measure this temp. Now subtract the smaller number from the bigger one. That will give you the delta T on the evaporator. Do I need to explain how to do it on the condenser? > When the outside temp is 85 degrees, the outlet temperature is 40 > degrees. That's a 45 degree differential. Coleman 13500 BTU. Mine will do that only when it's been cooling for a long time. If the interior is 85 degrees when the air conditioner is turned on, then the air conditioner will put out roughly 65 degree air. It will gradually cool the interior until it's putting out air not too much above freezing. SignatureD.J., N8DO; FMCA 147762 dj[underscore]osborn at yahoo dot com > > When the outside temp is 85 degrees, the outlet temperature is 40 > > degrees. That's a 45 degree differential. Coleman 13500 BTU. [quoted text clipped - 3 lines] > conditioner will put out roughly 65 degree air. It will gradually cool the > interior until it's putting out air not too much above freezing. Thanks. > -- > D.J., N8DO; FMCA 147762 > dj[underscore]osborn at yahoo dot com >> When the outside temp is 85 degrees, the outlet temperature is 40 >> degrees. That's a 45 degree differential. Coleman 13500 BTU. [quoted text clipped - 3 lines] > conditioner will put out roughly 65 degree air. It will gradually cool the > interior until it's putting out air not too much above freezing. It takes a long time for the air conditioner to get everything in the RV cooled down and until it does, it works like crazy seemingly getting nowhere. This is worse if sunlight is streaming in through windows and the RV is parked out in the open and not in the shade. SignatureRon P It isn't the fall that hurts:) It's the sudden stop:( > >> When the outside temp is 85 degrees, the outlet temperature is 40 > >> degrees. That's a 45 degree differential. Coleman 13500 BTU. [quoted text clipped - 19 lines] > > It's the sudden stop:( The time to cool down a hot anything, trailer, building, office, etc. is called Thermal Memory and is caused by the materials in the structure needing to be cooled down before they stop heating the structure. Same idea is why big cities stay warmer at night. LB snipped > The time to cool down a hot anything, trailer, building, office, etc. is called > Thermal Memory and is caused by the materials in the structure needing to be > cooled down before they stop heating the structure. Same idea is why big cities > stay warmer at night. > > LB Reminds me of a ritual Viola put me through every hot day. I'd spend the day inside either a shop welding or inside a pressure vessel down for repairs welding. Would come home and the two window units would be on full blast. House would be hotterinhell. I'd ask when she turned the ac's on and she'd say they'd been on all day. I knew they hadn't and would inform her of that. She'd throw a fit, then admit she didn't like them on. I'd then show her how turning them on in the AM after the nightly cool down, would keep the house cool all day. There was no way, after the house had baked in the heat all day two 6,000 btu units could cool down the walls. Now we have central air and it keeps everyone happy. HD in NY striving for perfekshun > The time to cool down a hot anything, trailer, building, office, etc. is > called [quoted text clipped - 3 lines] > cities > stay warmer at night. Almost--but not quite--right. Thermal *inertia* causes it to take a long time to cool them down. SignatureD.J., N8DO; FMCA 147762 dj[underscore]osborn at yahoo dot com > > The time to cool down a hot anything, trailer, building, office, etc. is > > called [quoted text clipped - 10 lines] > D.J., N8DO; FMCA 147762 > dj[underscore]osborn at yahoo dot com Define the difference between "inertia" and "memory" as applied to this case:-)) LB
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