We’ve got a 1998 Crown Victoria. Late last night, we started up the car, and turned on the A/C (there’s a “Max A/C” and an “A/C” button – we use “Max A/C” exclusively here in SE Louisiana). The A/C ran cold for about 10 seconds. Then we switched to the car’s “Auto” climate control and set the blower down to a lower setting.
Not sure if the abrupt switch to “Auto” and the lower blower setting means anything, but immediately upon switching over, the A/C started blowing hot. “Hot” like “just this side of a blow dryer”, not “tepid” – much hotter than the ambient air temperature, but not so hot as to be uncomfortable on the skin.
This morning, I tried the A/C again. Same blowing-hot results, so I opened the hood. AFAICT, there seems to be a single belt (serpentine, presumably?) controlling everything, and everything the belt was connected to was spinning. I couldn’t find an obvious component which seemed to be free from movement and free of a necessary belt.
I know what the compressor looks like, and I noted the tube which leads from the compressor to a more forward section of the engine, near the serpentine (?) belt. I don’t know what exactly this tube leads into (well, maybe it leads from some component in the front of the engine and to the compressor … or maybe not). The point is, though, that this tube connected to the compressor is decidedly cold to the touch – like a cold can of beer. There was plenty of condensation on that tube as well, but no ice that I could tell (is ice even a consideration for auto A/Cs like it is for a home A/C?).
Any and all, if anyone can lend any advice, it would be most appreciated. The main thing I’m hoping for is that an inexpensive repair is possible. I am concerned of bringing the Crown Vic into a shop tomorrow with zero knowledge, and subsequently getting sold a four-figure bill of unneeded repairs.
It could be a variety of things but the first thing I would look at is the heat selector doors inside the heater under the dash. As the Auto climate decides to put out warmer and cooler air to maintain temperature it will run a small motor to move a flap or door to redirect the airflow through the heater core, some cars change the amount of hot water flow through the heater core to acomplish the same thing they just direct all the air through it all the time. If yours if the water control type then the motor that controls the water flow may be stuck. It looks like the heat is just stuck on full hot. PS, the motor may be vacuum or electric.
A similar thing happened to my car - the AC got stuck on ‘nuclear’ temperature, and turned the interior of the car into an oven even in the middle of Winter.
The hot/cold air mix flap was controlled by a birectional motor that included a potentiometer directly connected to its little gearbox to give positional feedback. I never did work out what was wrong with it (but probably a famously dodgy Citroen electrical contact), as the act of dismanting and testing the system cured the fault spontaneously.
borderlond, you generally can’t access the air flow control/blower motor assembly from under the hood (bonnet); you have to access it via the dashboard. Take a deep breath and a day off, and strip down your dashboard (and maybe remove the steering wheel) to access the blower/air router assembly. It’ll probably be located near the floor, mid-way along the dash.
If you can’t immediately fix the problem properly, you could frig a temporary cure by removing the flap motor and controlling the flap manually with a length of stiff wire poking out of the dashboard fascia.
The Ford products that I’ve owned and serviced use a group of vacuum motors to operate blend doors. A box which contains the heater core, the A/C evaporator, and the blower fan will live beneath/behind the dash and will have 4 plumbing connections going through the firewall to the engine. In some models, the entire box is partially in the engine compartment and partially beneath/behind the dash.
Your owner’s manual will describe fuse locations, ampacity, and function, and there is probably one 30 amp fuse to protect the blower/compressor circuit. Hence, if the blower blows, and the compressor spins enough to make the suction line cold, a fuse isn’t it.
I’m thinking that the climate control selector is malfunctioning, and unless you’ve had some experience in disassembling a dashboard, you aren’t likely to have all of the tools and will manage to annoy the automotive trolls beneath the bridge while poking around, eventually driving the final repair cost up.
I was hoping to be able to access this stuff, if necessary, from the dashboard end, not from under the hood. I was also hoping to be able to do it without removing the dashboard.
Having to remove the dashboard moves it out of my severely limited auto maintenance experience, and moves the problem directly into “has to go to a shop for repairs I probably can’t afford, with a host of bogus repairs added on” territory.
Push the outside temperature button and see if it’s roughly accurate. Sometimes when driving in rain, my Thunderbird would suddenly start blasting full heat and only worked on manual. I pushed the outside temperature button and it said it was -40 degrees outside. I never did find the exact problem, but it has to be a loose connection to the sensor somewhere.
Looking at the compressor there are two pipes attached to it. One is a small (er) diameter pipe and one large(r).
In a normally functioning A/C system the small pipe should be warm / hot when the system is running and the larger pipe will be cool / cold. The small pipe will run to the front of the car to the condenser, the large pipe comes from the firewall (evaporator).
Assuming that this is what you are observing, and that the change from cold to hot was sudden and total, I am going to agree with MacGyverInSeattle about the position of the flaps / heater control valve. With one additional suspect, the control system might have packed it in. A heather control valve might be under the hood, or it can be under the dash. I have seen both.
The flaps are either mounted on the outside or inside the climate box inside the dash. This is probably not a do it yourself project! Depending on design, it may require the removal of the entire dash to access / repair the item in question. Repair costs can run anywhere from a few hundred to a couple of grand. I have had to remove entire dashes, so I could remove the climate box, so I could change one motor. We are talking about 12 hours of billable labor here. :eek:
As far as the control system goes, check all the fuses and see if any are blown.
On preview I see that danceswithcats mentioned that Ford products use vacuum to operate some blend doors. Check the vacuum suply hose and make sure you are getting suction to inside the car. A pinched vac hose can give problems, it will appear to have vacuum, but not a large enough quanity (If that makes any sense)
Oh, by the way
I am in the auto repair business, and I personally consider it to be uncool to go around insulting the people you are asking for help from. You might want to keep that in mind. You could also do a search for an excellent thread by Gary T on how to find a quality mechanic at an honest shop.
I’ll freely admit that stripping down a dashboard is a complete pig of a job. It takes long enough to find all the screws as some of them are cunningly hidden behind switches or air vent louvres etc., and there’s always one or two mouldings that snap off. I had to really psyche myself up to strip down the front of my cockpit, but I took the opportunity to fix an accumulation of minor faults - dodgy exterior temperature sensor, dodgy dot-martix display, dodgy fuel gauge, and lots of tiny dead lightbulbs.
My external temperature sensor is independent of the aircon circuit, and I believe this is generally the case. Rightly so, because all it does is measure the temperature of my left-hand wing mirror, which is way above the ambient air temperature on a sunny day. It’s quite difficult to obtain accurate temperature control within a car cabin as there are so many variables*, so most systems tend to specify “good enough” control, and to keep the system simpler there may be an inlet air temp sensor (usually fitted within the big blower/vent assembly) and one the air outlet, and maybe one or two in the cabin if it’s a fancy system.
*Including my favourites, infra-red heat radiated by the heat of the car’s interior surface, and the car’s occupants. On a hot day when my black interior is cooked by the sun to about 45 degrees Celcius the car doesn’t become comfortable until this heat is dissipated, which usually takes about 20 minutes of frostiest aircon blasting.
I apologize. The prospect of having to drop a couple of thousand dollars for this repair is especially vexing. The A/C in my personal vehicle has been out all year due to merely a snapped belt (not serpentine), and I have to forgo that repair.
If this was the car I drive around in, I wouldn’t care. But this is the car and wife and 2-year-old daughter drive around in. So the repair is both necessary (more or less) and impossible to afford (which for me, is anything over about $300-400). On top of that, we are new in this town, don’t really have time to track down a reliable and cheap mechanic, and will probably have to work with a mechanic we don’t know.
Perhaps you can understand the frustration. And again, I apologize – no insult to present company intended. There’s a heavy “distrust of the unknown” component at work for me … I admit that.
Look at the firewall on the car. There will be one or more small hoses (probably plastic) coming from the engine to and through the firewall. Follow them back to the engine, and verify that they are connected, and any rubber elbows are not cracked or disconnected. Then go inside the car remove the under dash panels in the area where the vac hoses come though and foll them to make sure the other end is connected. The hoses may travel to a vacuum tank, or to a solonoid valve pack.
Then start the engine, radio off, fan on lowest speed. Select various settings (defrost, face level, floor, cold, hot, recirculation etc) verify that the air distribution switches, and listen for any strange hissing noises A lack of air flow changing would indicate a vac supply problem. A strange hissing noises at one particular position would tend to indicate a leaking vac motor for that position. Of course if a fuse is blown the control head won’t send the signal to switch the vacuum so I have to ask: Have you checked the fuses yet?
I’ve looked at the fusebox, but I don’t know how to tell if those “newfangled” primary-colored type fuses are shot or not. They’re the ones with the numbers on them like 5, 10, 15, 25, etc. There’s a z-shaped wire inside of them – is that broken when the fuse blows, like a light bulb?
There’s also two fatter silver fuses in there … well, I guess they’re fuses.
I’ve always driven old cars, and I’m accustomed to the “glass”-looking fuses with metal ends. Those turn smokey when burnt up.
I’m looking for a 1998 Crown Vic fuse schematic online now. Yes, I can’t find my owner’s manual after our move (and yep – I wasn’t keeping it in the glove box ), so if I can’t find a schematic online, I’ll have to turn the apartment upside down to find the manual. I managed to find a fuse schematic for my Nissan truck one time, so I’m hopeful.
They are style ATC fuses. What you’re used to are type SFE and other glass fuses. The Z-shaped link breaks when the fuse element melts.
They probably aren’t fuses-more likely self resetting circuit breakers.
I doubt you’ll find it online at no cost. I recently ponied up $60 for a complete body wiring manual from Helm for my latest Ford purchase. A vacuum map book is another quest, with Helm being your best source. The books in auto parts stores never give enough data, IMO.
Yes the little z shaped wire burns up when the fuse blows. Also if you have a test light ATC fuses are great because you don’t even have to remove them to check them. There are two little tiny ports in the top of the fuse, one on each side of the fuse portion. If the fuse is good touching either port with a test light will cause the light to light. If the fuse is blown, you will only get a light on the supply side.
