Ford C350 Dual Air - trouble

[slawson2000]

The vehicle is a Ford C350 Centurion with Dual Air. For those unfamiliar with the Centurion, it was an option from Ford back before the Expedition to make essentially a four door bronco.

The FS10 compressor has locked up. One wet morning, turned on the defrost and I smelt something burning and shut it down. I thought electrical, but eventually found it to be the belt slipping on the locked compressor. With playing around trying to figure out the smell, probably 3 to 5 min run time.

The front ac system is pretty standard. The rear system tees off the exit of the condenser, flows to an expansion valve before the rear evaporator and then returns to tee in just before the drier/accumulator.

So, current plan.
Replace the compressor, drier/accumulator, condenser, and orifice. In the process blow out the remaining lines with shop air.

I have not seen the condition of the orifice tube yet, but I would like to know if I should replace anything else while I am in there (maybe expansion valve?) and some thoughts/tricks on the need to flush out the system. I would prefer not to have to dis assemble the entire system. I would also like to have all the parts that I would need here before I start.

I just notices that I am showing one post. I guess it has been a while since I have been here, but I got a lot of help from the old forum.

Appreciate the help in advance.

[bohica2xo]

FS10's usually lock up like that when there is no oil left in the system, or when someone charges them with liquid at a port very close to the suction port.

Was the system working ok to this point, or had it been sitting a long time? Any history would help.

Usually the oil loss happened with some refrigerant loss. You may have a leak someplace. I would start by pressurizing the system with a little 134a & using a sniffer to locate any leaks before I took the system apart.

Your parts list looks ok. Flushing generally means breaking the system in to individual parts.

If you can access the rear TXV I would pull it & check it for debris, then flush the liquid line from the condenser to the TXV.

Pull the existing accumulator, drill it & drain the oil in to a measuring cup. It may not have much (if any) in it.

Centurions were aftermarket conversions sold my Ford dealers, as new vehicles. Not all support parts are listed by Ford, so you may have to do some digging if you need something like a rear evaporator.

[slawson2000]

Yup, you nailed the Centurion. I have the option sheet somewhere. Interesting truck.

For the last decade or so, the truck sits for a couple months at a time, then gets used for a few weeks, then back in storage, Repeat. It has not had the AC serviced in years.

About 2 months ago, it went into daily use. At that time the AC was working. Nothing was added to the system.

The high pressure port area seems to have a wetter appearance than the rest. Not sure what it is. I attached a picture.

I do not have a sniffer. I have seen them from $20 to almost $300. If there is a cheaper one that will serve my purpose I don't mind getting one. Any recommendations? Maybe try a little dye?

I can pretty much get to the TXV. Should that get replaced as well or is that dependent on whether there is debris present.

Flushing... Is that the actual chemical flushing or blasting out with air? This is new to me.

Draining the accumulator... is that to try and figure out how much more to put in, or part of the diagnostics?

[bohica2xo]

Well, that hose / service port would certainly appear to be the leak. Nothing around it has any evidence of spilled or flung oil.

The question is, what was leaking. The service valve or the hose crimp. I believe that tube actually sits horizontal in the truck with the service port sticking up. If the port was leaking it should have oil going both directions from the port. Seems like there is more oil near the hose crimp.

You don't mention the model year of the vehicle. depending on year it may have had a tube & fin or a serpentine condenser. There may be an upgrade part available.

If it were my truck I would replace the port / hose assembly, and check all of the other hoses for oil stains.

Flushing the liquid line to the rear TXV should be done with both ends disconnected. A solvent is generally used, then blow it ALL out with plenty of dry air. Wait a day and sniff the end of the line. If you still smell solvent blow it out again. There is a lot of discussion about flushing solvents. If it is a metal line, you can use a very aggressive solvent like lacquer thinner without hurting the line. If it is a rubber line you need to be more selective on solvents.

The accumulator oil quantity gives you an idea of how much oil is still hanging around in the evaporators & suction lines. This is a starting point for the fresh oil charge volume when you are ready to put it back together.

I would also check the cycling switch for proper operation. On a cold morning the compressor should have been cycling due to the low heat load. If the switch or wiring has an issue the compressor could have stayed running at too low of a suction pressure.

[slawson2000]

The Centurion is a 1994 model with the 7.3IDI Turbo (Code K) four wheel drive.

The picture of the hose is from above looking down.

I threw some gauges on it this morning, 72psi (about 65F outside). I am not sure what the pressure should be. Do I have a leak or could that be something else on the hose? Dunno. I can replace that hose if need be. I see no other wet spots on the system.

How do you test the pressure switch with no pressure? The compressor is locked.

The condenser is a tube and fin (double row?) This truck always blew cold. But I do want to upgrade my 87 Bronco next go around. What would be the upgrade?

As for solvents, I guess I need to get a solvent flush guns and some solvent. I have rubber lines running to the rear. Any recommendations as to what to look for in a solvent? I don't know what is harsh or not. Any household stuff work?

I will measure up all oil as it comes apart. But at this stage it looks like I am replacing everything except the rear loop and the front evaporator.

[bohica2xo]

Looks like the entire line set for the engine bay is under 50 bucks:

http://www.ackits.com/ford-f-super-duty ... 7-94-47210

That part of the line set sees all of the underhood heat & engine vibration. I would just replace a 25 year old hose set at that point.

The condenser has been upgraded as a replacement part. New replacements are either 6mm Piccolo style parallel flow, or flat tube parallel flow units now. They drop right in, with all the right brackets & fittings already installed on them.

The switch is located on the accumulator. With 70 psi in the system it should be Closed. Pull the connector off of it & check it with a meter. Next, you can unscrew the switch from the accumulator. It has a Schrader valve under it. Once you have it off, it is at 0 psi. It should test OPEN.

Next is the relay and the clutch circuit. Leave the switch unplugged. Start the engine. Try the A/C. If the clutch engages with the pressure switch disconnected you have an electrical problem...

There are a few solvents on the market sold as A/C flush. Most have a high flash point & can take quite a bit of blowing to remove them all. We have a forum here dedicated to flushing & I am sure Tim can offer you a couple of choices if you call him. I use brake cleaner (safe for rubber) to chase slow solvents out, but that is not necessarily the safest way to do it.

The 87 Bronco you can stuff the 1995 condenser in (same as the one for your Centurion) It is 2 inches wider, and the discharge fitting is a #6 instead of the #8 that the 87 had. I believe you need the rubber grommets for the mounting points as well on the later condenser. Been more than 10 years since I did that

If the TXV is really clean, flushing that line is your call.

[slawson2000]

FYI. Thanks for hanging out on a Saturday...

I saw the same thing with the hose. May as well replace it. I agree.

You have a link to the Piccolo/Parallel/Flat condenser units? It sounds interesting, if not for this truck, maybe for the other.

Electrical all checks out as it should. All good.

I'll get back to you with what the insides look like.

[slawson2000]

So I have the orifice tube out. It was pretty stuck in there (so glad I had hemostats).
I do not think it looks bad. The oil had dye in it, quite bright. There was not much, but some almost graphite colored soot in some of the oil in the nooks and crannies. Not reflective like metal, but just grey. The odd thing was the build up of what appears to be plastic just above the o-rings. It is definitely plastic of some sort as it is flexible. I did not see or feel any metal chunks or parts in it.

Here are a couple of pics

[bohica2xo]

The usual powdered aluminum "soot" and some elastomer bits.

The dye is good news. A good blacklight should show any leaks.

Replacing the condenser should get most of any debris. Since the Tee fitting for the liquid line is before the OT, check the TXV for similar bits. Many TXV's have a screen on the inlet, some do not.

[slawson2000]

The plan is to check the valve today. I'll fill in the details after.

Was there a condenser upgrade for the Centurion?