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Doc Vegas · 03-15-2014, 05:09 PM

Folks: It's now into the 80's in Southern Arizona. Went out today after doing the CHF and realized the cabin AC system does not work. Pretty odd. Fan seems to work fine in normal "AC" setting, but no cool air. In "Max AC" the fan quickly goes from feeling normal to very low flow. If I turn it back to regular AC, the fan power returns - going back to "Max AC" it drops back to near nothing after a 30 seconds or so.

Regardless, the air it is blowing is not cool. The Rig was stored for a long time near the Gulf outside of Houston. We found wasp nests clogging the hot water heater and fridge vents. Could this be the wasps again? I have dropped more than $3000 since picking up this "lighting used" unit. I really hope the bleeding stops soon.

Advice would be greatly appreciated.

CBQ · 03-15-2014, 08:05 PM

Lightly used isn't always a good thing - most stuff on RVs break from sitting around untouched, vs. being used. (For example wasps could move in!)

Max AC vs. regular moves a damper to recirculate inside air vs. outside air. If airflow is dropping, there could be a damper issue.

This is likely unrelated to the AC not working. The compressor doesn't care what the damper setting is. Have the AC refrigerant pressure checked - if it has never been recharged it's likely to need recharging. Hopefully it doesn't have a leak or need a new compressor.

BFlinn181 · 03-15-2014, 08:36 PM

You'll have to look at the clutch on the A/C compressor while engine is running. If the inner part of the pulley is unmoving when A/C is off, then spins when A/C is on, the electric clutch is working and the unit must have enough coolant to keep low pressure switch off. If it doesn't kick in, then you probably need leak(s) found, fixed, then recharge system.
The air flow not working on MAX points to something obstructing the dampers or a dirty evaporating coil preventing air flow.

The fact that air flow changes when you change settings shows that the vacuum or electrically operated dampers are working. For safety reasons, if their was no vacuum, the air flow is all diverted to the defroster vents.

mus289 · 03-15-2014, 09:17 PM

To check if vacuum leak is causing your problem, when you switch your control from Norm AC to MAX AC and flow out of vents drops off see if you are now getting flow out of your defrosters. As BFlinn181 mentioned, if vacuum is low your air flow is directed to the defroster to ensure a clear windshield. During storage some critters may have chewed on a vacuum line. Had similar problem with my rig and it was a leaking vacuum line. Good Luck!

Doc Vegas · 03-16-2014, 12:38 PM

Thanks guys. Where would the vacuum lines be located???

BFlinn181 · 03-16-2014, 12:46 PM

Vacuum come off the intake manifold to a reservoir, then through firewall to under dash. It connects to HVAC control, then various thin plastic tubes to each vacuum 'motor.'
You need to check that the A/C compressor is working. In addition, you might have a problem with the heater core shut-off valve. It stops engine coolant from going into the heater core when you don't want heat. If the valve remains open, your A/C will be cancelled out by the heater. To check, feel hoses going to heater core, they shouldn't be hot if coolant isn't flowing.

Unless you've worked on HVAC systems before, you might consult a professional. Any HVAC tech can do it, it doesn't require a Ford or RV specialist.

Fiesta48 · 03-16-2014, 03:33 PM

"Lightly used" means nothing. I've saved way over $100,000 on learning how to fix things myself. My lightly used '11 Bounder had 49 minor issues. Taking it in at $50-100 each would cost a fortune. Get shop/service manuals, and ask questions on the internet. The internet has saved me tens of thousands of dollars.

Doc Vegas · 03-16-2014, 07:55 PM

Update: I went to AutoZone and picked up a $35 can of the cooling gas. Much to my amazement, when I turned on the rig, it was blowing COLD air. I went out to look "under" the hood and could hear the compressor kicking in and out. I was too slow to the "freon" can. When I hooked up the gauge, I could see the pressure drop whenever the pump kicked on. However, when the pump kicked off the pressure would skyrocket and peg the gauge. By the time I got ready to send in the new freon, it was too late and the pressure was high and the pump did not kick back on. I shut it off and turned it back on, still no compressor. Do I have to wait another 24 hours? Weird.

BFlinn181 · 03-16-2014, 08:07 PM

Quote:

Originally Posted by Doc Vegas

Update: I went to AutoZone and picked up a $35 can of the cooling gas. Much to my amazement, when I turned on the rig, it was blowing COLD air. I went out to look "under" the hood and could hear the compressor kicking in and out. I was too slow to the "freon" can. When I hooked up the gauge, I could see the pressure drop whenever the pump kicked on. However, when the pump kicked off the pressure would skyrocket and peg the gauge. By the time I got ready to send in the new freon, it was too late and the pressure was high and the pump did not kick back on. I shut it off and turned it back on, still no compressor. Do I have to wait another 24 hours? Weird.

Using the single gauge attached to a can of freon doesn't tell the whole story. You need an A/C manifold gauge set that has connections for high and low pressures. You were hooked up to the low side. When the compressor goes on, it will draw from that side, showing lower pressure. When it stops, the built up high pressure goes through the expansion valve and the condenser and shows high pressure from heat build up. That's why the rooftop A/Cs have a delay built in so they don't try to operate while the pressure is high and perhaps stall the compressor motor.
The single gauge (low side) fill kits are notorious for allowing you to overfill the system, reducing cooling capacity, causing leaking seals, blow outs or compressor problems. The only proper way to monitor A/C health is with a proper set of manifold gauges.

DSST-Storm-T · 02-22-2015, 11:26 PM

I believe that I am working with a similar issue in my new motor-home.

I am always getting heat, I can cancle some of it out with the AC. From the sounds of it, looks like heater core shut-off valve is not working properly, time to track this bug down.

Thank you, this information was just what I needed to get started.

Quote:

Originally Posted by BFlinn181

Vacuum come off the intake manifold to a reservoir, then through firewall to under dash. It connects to HVAC control, then various thin plastic tubes to each vacuum 'motor.'
You need to check that the A/C compressor is working. In addition, you might have a problem with the heater core shut-off valve. It stops engine coolant from going into the heater core when you don't want heat. If the valve remains open, your A/C will be cancelled out by the heater. To check, feel hoses going to heater core, they shouldn't be hot if coolant isn't flowing.

Unless you've worked on HVAC systems before, you might consult a professional. Any HVAC tech can do it, it doesn't require a Ford or RV specialist.

BFlinn181 · 02-23-2015, 12:05 AM

Check and see if the heater control valve is mechanical, with a 'choke cable' type sheathed push/pull cable or vacuum controlled. It's not unheard of a vacuum motor or hose to leak enough to prevent it from closing fully. You could also do what school bus fleets have done for decades, put a simple shut off valve in the heater hose as it enters the heater core. Turning that valve shut meant no flow until you twisted it open. The buses I drove never had A/C, turning the valve made it livable in the driver's seat in warmer weather!

Patti Jean · 02-23-2015, 03:59 AM

As the ambient temp increases or decreases, the system pressure changes. Maybe you got the compressor to kick in temporarily because of the outside temp increase during that time. When it kicked the compressor clutch back in it may have dropped the system pressure back below its low limit. You can try to put a little freon into the system to see if it will pressure the system high enough to allow the compressor clutch to kick back in or you can jump the compressor clutch back on with 12v temporarily, and charge a small amount into the system. Watch the pressure and be careful!

Doc Vegas · 03-02-2015, 10:30 PM

Wow, cool this got resurrected. I am surprised myself that the original post was a year ago. Ironically, the RV is at the shop now. So far, the costs are around $600. When i get it back I will post up what they found, but something about lines being bad some some of stuff that I had never heard of....

DSST-Storm-T · 03-04-2015, 10:24 PM

I had performed some additional testing on my RV and found that If i had it running without the AC and changed the temp selector from Warm to Cold it did eventually cool down after about 5 min. I surmise that the heater core shutoff valve is working properly and this is the amount of time required to cool the heater core. If I then turned on the AC it wouldn't get any cooler, if there is an air dam/diverter in there i don't know but ether it's not working or the AC is not working or both. It's an item i found during our purchase walkthrough so it's in the shop getting worked under warranty.

Ok, this is a try at a signature block...
2015 Fleetwood Storm 32H, With CHF on both Front and Rear, MaxxAir2 coverson all vents, Warm white LED lights on the way.

Possible Future plans "Zapp 3000W charger/inverter/auto transfer switch" unit, upgraded batteries (4 6v) and possibly some Unisolar 144w panels.