How tight/how to know roof a/c

[Khenson]

I have been tracing a leak for sometime in my motorhome. Today, I decided to take a forum members advice and check the roof a/c bolts (the 4 under the cover from the inside). Wow! I could move them by hand with little effort. So I got tighten happy...later realizing maybe too happy. I know that if I tighten these too tight that the problem could be worse. So, here is my question:

How do I know how tight to tighten these bolts? Also, how can I check the gasket to make sure it is not compressed to far?

Thanks!

["007"]

I'd tighten till snug and then remove AC cover on roof and make sure your drain holes are clear some coach AC's have drain tubes that can plug also.

[Dixieray53]

After you tighten the bolts...Caulk all the areas. Then get your hose and flood the bolts...Check for water leaks...Caulk solves most problems...D

[hoppers4]

Here's a piece of the installation manual for the Duotherm Briskair AC unit.

EVENLY TIGHTEN MOUNTING BOLTS TO A
TORQUE OF 40 TO 50 INCH POUNDS.
This will compress the roof gasket to approximately
1/2". The bolts are self locking so over tightening is
not necessary.

Here's another piece of information from a Duotherm Sunchaser rotary XL and Classic series

Evenly tighten the four (4) anchor bolt nuts (D) to
secure the unit and insure a proper roof seal. Since
these nuts have lock washers, do not over tighten,
75 in. Ibs. or 6 1/4 ft. Ibs. torque is recommended.

Proper installation should preclude caulking.

Your model may be different. Perhaps a Google search for an installation manual for your model will provide the correct info.

[Khenson]

Ok...I thought you had to loosen the 4 bolts to remove the cover on the roof. Not so?

Also, I read elsewhere to never caulk around the a/c gasket; so, where do you caulk?

Again, thank you.

[TXiceman]

Above all, do not caulk the A/C unit. That is a stop-gap measure.

First try tightening the 4 bolts from the inside. They are just snugged. If that does not work, check the drain holes up top.

Last thing is remove the A/C and put a new foam gasket under it. The newer high density gaskets do not compress as bad as the older ones did with age. With a new basket, tighten it until it is compressed by 1/2 of the original thickness.

Ken

[Khenson]

Ok thanks all. I don't think I am being clear about my question of how to know if I have tightened to 1/2 thickness without removing the unit, which requires loosening the bolts and removing the unit. I don't see a way to remove the outside cover and inspect the gasket and/or drain holes while the bolts are tight.

I'll go take a second look at it tomorrow.

[TXiceman]

You can see te gasket by removing the inside cover. You can only tighten to 1/2 the original thickness only with a new gasket.

6 to 8 ft-lb to tighten the gasket is not much. You can just snug it with a nut driver. But snug it evenly.

As for getting the top off, some units have 4 nuts on top with washers under them and others have 4 screws on the lower edge, two on each side. The the top cover simply lifts off. Some will require you to rock the cover forward.

Good luck.

ken

[BZam]

Originally Posted by Khenson

I have been tracing a leak for sometime in my motorhome. Today, I decided to take a forum members advice and check the roof a/c bolts (the 4 under the cover from the inside). Wow! I could move them by hand with little effort. So I got tighten happy...later realizing maybe too happy. I know that if I tighten these too tight that the problem could be worse. So, here is my question:

How do I know how tight to tighten these bolts? Also, how can I check the gasket to make sure it is not compressed to far?

Thanks!

I had a pretty good leak in bedroom area this winter after we had a couple of 100 year rains. As I had sealed the entire roof with Ethernabond tape I took it in to get new seals in both ACs. They found the problem when removing the units. The lag bolts had not been sealed with silcone in factory. Some say this could not be case but I know of others in my year group who have had same problem. Anyway when I picked it up the tech showed me the old bolts and how they had detiorated and that was the leak. So he put in new seals, new bolts and sealed them properly. Hopefully that will correct my leak.

We have had a couple of good rains since and no sign of leak.

Bob

[Khenson]

Got it, thanks!

Originally Posted by TXiceman

Above all, do not caulk the A/C unit. That is a stop-gap measure.

First try tightening the 4 bolts from the inside. They are just snugged. If that does not work, check the drain holes up top.

Last thing is remove the A/C and put a new foam gasket under it. The newer high density gaskets do not compress as bad as the older ones did with age. With a new basket, tighten it until it is compressed by 1/2 of the original thickness.

Ken

[Khenson]

Bob, thanks...I'll be sure and check that thoroughly!

Originally Posted by BZam

I had a pretty good leak in bedroom area this winter after we had a couple of 100 year rains. As I had sealed the entire roof with Ethernabond tape I took it in to get new seals in both ACs. They found the problem when removing the units. The lag bolts had not been sealed with silcone in factory. Some say this could not be case but I know of others in my year group who have had same problem. Anyway when I picked it up the tech showed me the old bolts and how they had detiorated and that was the leak. So he put in new seals, new bolts and sealed them properly. Hopefully that will correct my leak.

We have had a couple of good rains since and no sign of leak.

Bob

[BZam]

Originally Posted by TXiceman

You can see te gasket by removing the inside cover. You can only tighten to 1/2 the original thickness only with a new gasket.

6 to 8 ft-lb to tighten the gasket is not much. You can just snug it with a nut driver. But snug it evenly.

As for getting the top off, some units have 4 nuts on top with washers under them and others have 4 screws on the lower edge, two on each side. The the top cover simply lifts off. Some will require you to rock the cover forward.

Good luck.

ken

Depends on configuration. On modern diesel pushers with ducted air you cannot get to units from inside. To remove the ceiling you have to drop cabinets and its not for most of us.

But on older units, like my old 1990 Fleetwood, I could take the bottom cover off and periodically tighten the seals.