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Coolant leaking from A/C drain tube

VIN number 8AFBT23D156458041
Region Argentina
Mark Ford
Year 2005
Serial Number 458041

Leads to what the problem might be?

Leaky heater core.
As a test disconnect the hoses to the core and plug them or tie together with a barrel fitting; see if the leak stops.

Bad heater core.

As a quick fix, if I bypass the core, do I’m eliminating heater and AC function?

If you connect the heater hoses together with a hose barb and bypass the core, you will eliminate the heater, but the AC will still work. You won’t be able to control the vent temp, it will be either very cold or cabin/outside temp.

There is one very remote possibility, very rare but possible. If one of the heater core hoses is leaking right at the connection, where the leak is between the hose and the pipe, as if the clamp weren’t tight, and the seal around the core pipes is not completely sealed, coolant could be seeping around the connection and following the core pipe into the interior where it eventually drips out the AC drain.


Mechanic had it for a day and car didn’t leak any coolant, though he found few minor cracks under coolant tank. No leak by the heater core found, coolant tank replaced. Now, no leaks so far but after AC use, steam with coolant smell comes out of center vent.

I guarantee you the heater core is leaking, as the others have already said.

“steam with coolant smell comes out of center vent.” . . . the only possible way you get that scenario is with a leaking heater core

“Mechanic had it for a day and car didn’t leak any coolant” . . . did he pressure test the system?

In any case, when the mechanic has the old heater core on the bench, he will probably see the leak

Look at it logically. Those pictures show the ac condensation drain tube, and there’s obviously coolant coming out of the pipe. There are only 2 major components in the evaporator housing. The evaporator and the heater core.

Is there a sticky film on the inside of the windshield?

All roads lead to Rome

In your case . . . All roads lead to the heater core

@db4690 Yes, this is an obvious case of heater core leaking or the connection at least. I had a Chevy Caprice with the same symptoms into the local nearby GM dealer, and they hummed and hawed about what might be the problem. I got on the cell phone with my regular mechanic who told me it was the heater core and what it would cost to fix it; $250 in this case. He was $5 off!.

It’s a rare car in which the heater core can be replaced for $250…

Must have been a '77 Caprice…


Does it get very cold where you’re at?

If it does, I would highly suggest replacing the heater core, versus bypassing it


“It’s a rare car in which the heater core can be replaced for $250…”

Yes, indeed

In my experience, it’s usually been vans and trucks, and usually the ones in which half of the housing is in the engine bay

In some of those fortunate cases, there was an access plate under the right dash.

Or in other cases, there was a part of the case that said “cut here” for heater core service


What kind of Ford do you drive?

If we have the same car here in the US, perhaps one of us will be able to give you some more detailed advice

@Caddyman This was a 1988 Caprice which is relatively easy to work on. I agree that on a lot of cars there is 5-10 hours of labor involved in the late 90s. The worst I’ve seen was a Mitsubishi Montero, where the vehicle seems to have been built around the heater/A/C system, requiring a complete disassembly of the dash and related interior. It took 12 hours of labor to complete.

Hi why would passenger flor may be wet and same side windshield fogged up if I bypassed heater core. I see no fluid railing into firewall clamps are tight. Maybe it happens when I drive more pressure and can’t see? Is there any other way to loose fluid back there? Also anyway Water is stuck in firewall and not draining?


because your ac condensation drain tube is probably plugged up or disconnected

Do this . . .

Go park the car outside over a dry section of driveway

start the car

turn the ac to max cool

pop the hood

make sure the ac compressor is engaging

go in the house, but leave the car idling

drink a cup of coffee

go back outside

is there now a puddle of water underneath the car, roughly where the ac condensation drain tube is?

If there isn’t you know it’s either plugged up or disconnected

If you live in cold country, a place where temperatures often go below freezing in the winter, then you are probably used to seeing water condense on the inside of your windows. The window glass gets very cold and when the warm moist air inside the house hits those cold panes of glass, the moisture condenses out and you have water on the inside of the glass.

Even if you bypass the heater core, if you run the AC, and it runs if you are in defrost mode even in the winter, the evaporator core located in the ducting inside the vehicle gets very cold. Even in winter with no heater, if you are driving, you are giving off body heat and moisture inside the vehicle. You may also get some solar gain if the sun is shining. The warm moist air starts to condense on the inside of your windshield fogging it up, so you turn on the defrost which turns on the AC. The warm moist air gets colder and condenses in the evap core and drains down into a tray under the core.

There is a drain tube that drains the tray through the firewall. If it plugs up, then the tray overfills and dumps onto the passenger floor and fogs up the windows on the passenger side.