Brakes Locking (again) and Weak AC

[SantaCruzin]

Well, it always seems that each RV trip ends up with a few more questions for the forum, my apologies! We just got back from what was to be a 4-day lake trip but ended up at 2 days because of the forecasted temperatures of 105º+ and the two issues I'm about to describe. For background, we have a 1996 24' Jamboree Searcher with just under 40,000 miles on it and we were towing a boat, totaling about 3,000 lbs with the trailer.

1. We had an issue with our brakes last summer where the front left brake caliper seemed to stick, resulting in a VERY hot disc which we luckily caught before it got too bad. Loosening the caliper bolts and working the caliper back and forth a few times loosened it's grip on the disc and allowed us to make it to our destination and back (60 miles total). I then took the RV to a shop and had them do a "full" brake job, flushing the system and giving everything a once-over (I'd just replaced the discs and pads in the front before this all happened.) We then did a 300 mile trip trouble-free before the RV sat for about 7 months with the exception of a few little day trips near our home.

Well, on this trip we made it about 65 miles (including over two mountain passes) before I noticed a smell, quickly pulled off the freeway, and found some flames licking out from the front left and I think some smoke coming off the front right (it could have been blowing over from the left side). 30 minutes later I'd done my normal procedure (cap off the master cylinder, loosen bolts, bang bang, back together, and good to go) and we made it the remaining 70 miles to our destination. The caliper locking up happened after a section of road connecting two freeways where we were stopped at a few red lights for a few minutes. SO, I am thinking this either has to do with my foot pressing too long or hard on the brakes while stopped, or the heat causing some sort of expansion while sitting. In either case, would I be correct in assuming the brake caliper is the culprit here?


2. Our AC was definitely having a hard time keeping up with the 95º heat, though it was not so bad that we could not be inside relatively comfortably. It did make me nervous about 10º warmer weather though, and we decided to cruise back home before it hit. When we left, a large amount of what I assume to be water fell down from the ceiling and onto the carpet in the RV. Any idea what this could have been from? Any suggestions on a fix? I'd prefer not to have to take the RV to someone if I don't need to.


Thank you all very much!

 

[Gary RV_Wizard]

I'd agree its a brake problem, some part of the caliper mechanism.

Where did the water fall from? Around the a/c air intake, or elsewhere in the ceiling? Is it a ducted a/c, or does the chilled air blow directly out of the ceiling unit? In humid weather, a lot of condensation can accumulate on the ducts when the a/c runs non-stop. Or there can be a lot of condensation right around the a/c itself if adequare air isn't flowing through properly.

 

[SantaCruzin]

Thank you for the quick reply, Gary!

And yes, important details I left out! Doh! The water fell from the intake in the center of the RV, which is right below the unit as near as I can tell. The AC is ducted, coming out of ceiling vents in the rear, middle, and front of the RV. I was used to a lot of water coming off the roof OUTSIDE the RV, but was surprised when it came sloshing out of the ceiling INSIDE the RV.

 

[Ernie n Tara]

AC is quite possibly condensate overflowing the catch pan. I'd check that the drain is not blocked.

The brakes could be the caliper as Gary noted or the brake hose liner may be collapsing and trapping fluid under pressure against the caliper

 

[mel s]

SantaCruzin,​

Out of adjustment rear drum brakes can cause one, or both, front Disc brakes to drag...(A brake adjustment may correct the problem).

 

[SantaCruzin]

SantaCruzin,​

Out of adjustment rear drum brakes can cause one, or both, front Disc brakes to drag...(A brake adjustment may correct the problem).

Thank you for that! In theory, they were correctly adjusted by the shop. While it's been 10 months, there was less than 500 miles of driving in those 10 months.

 

[Kirk]

I am not a brake expert, but experience has taught me that when an RV sits idle for an extended period it is not uncommon for rust to form on calipers and make the brakes drag. I mostly had that experience when spending an extended period in the pacific northwest. I would agree that they should have been adjusted properly when it left the shop, but if it sat all winter where there is much humidity, that could cause it to come back.

On the water from the ceiling, that sounds to me like the condensate is not draining out on to the RV roof, like it should, as Ernie has suggested. That too is not uncommon as mold can grow in the drains and prevent the moisture draining out on the roof. Your A/C has a catch pan under the interior coils that has a drain line that empties to the roof, when draining properly. It can be cleaned and flushed with a chlorine bleach mix to prevet it growing right back.

 

[Henry J Fate]

Replace both front brake hoses.

Clean out the ac from roof side. To get to the evaporator coil, it requires removal of the skin around it. You can clean out the evaporator coil from the inside with a garden hose and spray nozzle. Use caution and have the coach level. Have a wet vac available and easy on the spray so that it doesn't back up

The condensate drain system on a motorhome is a little different than a home window ac unit. It must be able to dispose of water in varying pitches and level. A good cleaning will keep things moving. You can spray a mold and mildew remover prior to cleaning out.

 

[Gary RV_Wizard]

The condensate on the outside is not supposed to be able to drain to the inside of the RV, but it has been known to happen if something else is awry. There is not supposed to be any path for water to get in around the upper a/c section, no matter how much water collects on the roof. Bad gasket or insufficiently tightened clamps are possibilities.

 

[Kirk]

The condensate on the outside is not supposed to be able to drain to the inside of the RV, but it has been known to happen if something else is awry.

There is a catch tray under the inside cooling coils that can be seen if you remove the inside grill from the ceiling. It is at the bottom of the coils to collect moisture condensed from cooling the interior air and that tray has a drain to the outside and on to the RV roof. Best access to clean it is from the roof by removing the evaporator cover. I have done this many times.
R.V. Air Conditioner Leaks

 

[SpencerPJ]

About your brakes, Could it be a failing rubber brake hose that does not play nicely when things get heated up? That could explain working for little short trips, problems on the road? Just a thought.
Sometimes RV shops might not have the best mechanical mechanics to do those types of services? A fluid flush (and it was the right thing to do) could have loosened stuff that got lodged in various connection manifolds.

 

[Henry J Fate]

The condensate on the outside is not supposed to be able to drain to the inside of the RV, but it has been known to happen if something else is awry. There is not supposed to be any path for water to get in around the upper a/c section, no matter how much water collects on the roof. Bad gasket or insufficiently tightened clamps are possibilities.

Yes. True.
The moisture (condensation) in the rv system begins at the evaporator core which is mounted on the rv interior side of the air flow. This moisture is supposed to drain to the outside. If blocked, it can back up into the interior through the ceiling filter grille.

It appears that this was the case however, it may have been outside moisture that found its way in through a gasket or some other failure.

It would be a good idea to consider both possibilities as being the culprit and take the needed action.

 

[TheBar]

Brake calipers and/or master cylinders can lock up for lots of reasons. If the brakes get way too hot (you mentioned going down 2 mountain passes) calipers and rotors can warp out of shape. A warped rotor usually causes a pulsing effect when the brakes are applied. If there is any moisture in the brake fluid it turns to steam and expands when the brakes get hot, moisture can also cause the master cylinder and caliper pistons to rust and lock up, air in the lines will expand when hot, and dirt or rust in the fluid can jam the master cylinder or caliper pistons. Caliper slide pins can rust and bind keeping the pads from backing off, or if bent cause the pads to bind and not back off.

 

[John From Detroit]

I do not know about your rig but I know early to mid 2000 Workhorse Custom Chassis motor homes had a recall for exactly that issue.

 

[SantaCruzin]

Thank you all for your insights. I am pretty good at staying off the brakes and using the transmission to slow our descent. On most downhills, I can successfully avoid using the brakes more than 2-3 times (only used when approaching a few tight corners on Highway 17). So while it is certainly possible that heat is the culprit (and I will investigate all you've pointed out) I am leaning more towards something related to my foot staying on the brake pedal for an extended time while at stop lights. I don't know if this is duration or amount of pressure (foot held down hard while waiting at a light) but in both instances it happened after waiting at various stops.

An important detail which I left out: the first time it happened was about 5 miles after leaving my house and driving through town. This was not while towing and we had a minimal load with just my father, daughter, and I heading for a short 2-nighter. While it was a VERY hot day, brake use was at a minimum.

 

[ChasA]

Your brakes are not going to heat up from keeping your foot on the brake pedal while stopped.

 

[SantaCruzin]

Your brakes are not going to heat up from keeping your foot on the brake pedal while stopped.

Right, sorry. That is what I meant by "Heat is not the culprit." I am wondering if it's the caliper piston extending too far or being extended for too long which is not allowing it to retract. I don't think the brakes were getting particularly hot in either scenario due to trying to be careful with the amount of brakes I used and the fact that the first time it happened within 5 miles of home.

 

[House Husband]

The calipers on your MH are not one of Ford's better ideas.
They require biannual service.
Remove calipers by driving the 2 spring loaded mounting pins out. Clean all surfaces and lube with special synthetic brake grease and reinstall. Also the phenolic pistons in the calipers will swell and seize over time. If the pistons are difficult to push in then new pistons and seals are required or rebuilt calipers.

Richard

 

[Ray-IN]

On a 1997 chassis the flexible brake lines should have been replaced at least 2x by now. They appear fine but inside the lining gets bubbles in it, then flakes off, clogging the line enough brake fluid cannot return to the master cylinder.
Remember, brake fluid in under pressure flowing into the calipers, it is under no/little pressure making the return trip.
BTW, did you know Ford, Mercedes, and several other auto mfgrs. recommend replacing brake fluid every 2-3 years? ref: Debunking Common Myths about Car Maintenance
Honda states every 45K miles or 6 months, ref: Honda Accord Maintenance Schedule and General Information

 

[Skookum]

I'd be inclined to have two new front calipers put on there if you've already done pads, rotors.
Going upstream and checking brake hoses is a good idea. They can collapse and cause sticky calipers although in my experience I've never seen one.
Upstream from that should be a proportioning valve. These can fail or get gunk in them.
Your master may need to be rebuilt if a return spring is failing.
It's got some kind of booster. I'm not familiar with this exact setup, but generally there is a rod that the booster pushes to engage the master. If this has been mucked with, extended, it may be causing intermittent brake drag. Had this issue on a car of mine where someone replaced the rod between the booster and master with a bolt. The idea was, by lengthening the rod, that would take up some of the free play in the pedal. Older delco systems are notorious for this. However, the "rod" was too long, a poorly hacked bolt, and the threads were catching, not allowing the master to fully release when letting off the brake. I went through pads, rotors, calipers, hoses, proportioning valve, and a new master before I discovered the issue and got the bright idea to also disassemble the booster.

Good luck!