I'm working on an 02 altima at work. I put a heater core in it, refilled it with coolant, and the heat was fine. sent it out.
It came back a few days later, no heat. Customer has it set to Full heat, Blower motor on max, and Max A/C (first question, why the hell do you have A/C on when you want heat?)
I bled the system again, and the heat was fine. I drove it, heat was still fine. turned it to Max A/C again to make sure, and it gets colder and colder. The heat should overpower it, it should lose a little bit of it's edge, but it should still be hot.
So we dug a little deeper.
Car has aftermarket rad hoses (some universal junk, cut jagged, the hose clamps are cut so badly that I kept snagging it on my arm and cutting myself on it.
The heater core return hose is not as warm as it should be, so I checked the "water control valve". It was an aftermarket unit, installed backwards. Flipped it around, same deal. Great heat until you hit the A/C button.
(it has decent heat even with A/C on off idle, but idling, it's nothing.)
Installed a new, OEM thermostat and an OEM water control valve, no change.
Found a bulletin on a similar problem, followed the bulletin. No change.
Coolant was 29% glycol, flushed it all out (with a vacuum filling machine, so there should be NO air bubbles present), ensured there was a vacuum pulled on every part of the system (heater core hoses were sucked in, even) and refilled with a better mix. No change.
Does anyone have any ideas?
If I pull off the heater core return line, water is pushed out, which tells me the core is not blocked (it damn well shouldn't be, it's brand new), but it isn't pumping as much as it should, imo. It should pretty much be flooding out.
The only thing I've came up with is that the water pump is not pumping enough, but it has decent heat right up until you hit the A/C button.
It really makes absolutely no sense.
I tried to call Tech Line on it today to see if they had any ideas but they were too busy to accept calls. So I guess I'll be wasting time on the stupid thing tomorrow too.
Do any of you guys have any ideas on what to try?
Seems like a normal condition.
The two, heat and cooling are offsetting each other.
When you really need heat the AC won't engage anyway.
Below 40F or close.
Shouldn't the coolant be 50% glycol ?
iceracer wrote:
Seems like a normal condition.
The two, heat and cooling are offsetting each other.
When you really need heat the AC won't engage anyway.
Below 40F or close.
Shouldn't the coolant be 50% glycol ?
I didn't know cars still use a water control valve anymore.
Most don't.
In most cars, the AC and MaxAC do different things. Normal AC draws air from outside meaning through the heater core. Will cool the heated air but not usually to AC levels. Been told that running AC with heat acts as a air dryer and will defrost windows quicker. Max AC draws air from inside the car and recirculates the air, drawing in cooler air means output is colder. I've been told that on some newer cars is might not go through the heater core in this setting.
yes it is supposed to be 50%, I sucked it all out and refilled with 50/50
and I've been trying to find a diagram of the flow, to see if it runs over the heater core when in max a/c
I've never checked one with max a/c usually the test to see if the heat is good enough is to just cut on the AC and see if the heat will overpower it. it should only lose a little heat, not all of it.
called Techline and they said it sounded like a flow problem. Was involved in a major accident a few years ago. I can tell pretty much all the cooling system has been replaced, they told me to throw a radiator in it.
Radiator installed, same problem.
They said the history showed that people kept getting rid of this car, I'm guessing because of this stupid heating problem.
Even with max AC, heat is decent at like 2500 rpm, cold at idle.
i dont know.
Looking at my Escort Shop Manual again, Air does not go through the heater core in Max AC or just AC.
In all other positions, air goes through the both cores.
Has anyone mentioned that "Max A/C" usually shuts off water flow to the heater core?
Knurled wrote:
Has anyone mentioned that "Max A/C" usually shuts off water flow to the heater core?
This is what I was thinking too, but after talking to two people at Tech line and every tech in the shop (including the master tech whom I apprentice for), they have said that it still runs through the heater.
i dont know.
The problem doesn't make any sense if the water still runs through the heater with the AC on.
Techline's latest solution is to leave the cap off with the front raised over the weekend to bleed it out, even though I've literally ran through half a tank of gas bleeding the cooling system.
the only thing that makes sense is if it won't flow through the heater with AC on.
But the AC is on with defrost on, correct? and, in these pieces of E36 M3, at least, in order to cut the AC OFF after putting it in defrost, you have to cut the car off. Really awesome, huh?
I'm so sick of seeing this stupid green altima and I'm so sick of working on it every day and not getting anywhere. I even went as far as to swap the heater hoses in case I hooked it up backwards (I didn't)
I blew water through the brand new heater core and it isn't blocked. The new rad isn't blocked, the only things left are the water pump and the engine.
I told Joe (the master tech) we should just put an engine in it because if we do that, it'll come with a damn waterpump. Then we will have replaced the entire cooling system, and it'll probably still not have heat with the AC on.
Inferior replacement heater core?
Kenny_McCormic wrote:
Inferior replacement heater core?
it's not blocked, for sure. and I REALLY don't want to do the job again. it's a bitch.
lol
i don't know what we're going to do about it.
Is the mix/blend door motor changing when the max A/C button is selected (you're talking about the fresh air/recirculate button right?)
In reply to corytate:
Unless its normal function for the box to automatically kill the heater on max AC, thats all I can think of. The new core doesn't have as many rows/surface area/flow.
I don't know. Neither of the last two AC equipped vehicles had any coolant shut off.
In max AC/recirc. the air bi -passes the heater core anyway.
it sucks because I can't find anything in the FSM saying whether or not it bypasses the core in AC or recirc mode, so I can't print it off and attach it to the customer.
'Low coolant flow', was that with the engine running? If so, there's a long shot that the water pump impeller could slip on the shaft causing reduced coolant flow, Mazdas had that problem some time back.
But, if you flip it to Max A/C and it quits, I'd be REAL tempted to investigate any vacuum hoses. Max A/C means the recirc door closes, blocking off outside air. If somehow the Max A/C vacuum has been redirected to the blend door actuator (I assume they both work on vacuum) then that could be your problem. If the recirc and blend doors are cable operated, well damn I got nuttin'.
Curmudgeon wrote:
'Low coolant flow', was that with the engine running? If so, there's a long shot that the water pump impeller could slip on the shaft causing reduced coolant flow, Mazdas had that problem some time back.
But, if you flip it to Max A/C and it quits, I'd be REAL tempted to investigate any vacuum hoses. Max A/C means the recirc door closes, blocking off outside air. If somehow the Max A/C vacuum has been redirected to the blend door actuator (I assume they both work on vacuum) then that could be your problem. If the recirc and blend doors are cable operated, well damn I got nuttin'.
I know the blend door is cable operated because they have a recall wherein the little gear falls off the case. Last heater core on an altima I did came back with no heat, and we discovered that wonderful little gem. At least that one wasn't my fault.
The water pump is pretty much what I'm down to now, but it still doesn't make sense that it is fine until max ac or defrost is cut on. Wish I could find ANYTHING or ANYONE to confirm for certain that flow is cut off to the heater core when in recirc=/
I'm at a loss on this stupid car.
unless maybe the extra load from the compressor engaging is causing the water pump to slip when it normally doesn't????
So what is the point of having a water control valve if it's not supposed to shut off flow to the heater core when you're running on max a/c? I would tell the customer to quit being stupid and quit running the heat on recirc. My xterra won't let you turn on recirc when the vents are set to defrost with any combo. Maybe I should go see if I can run max ac with the heat on and see what happens
Update: so I tried running the heat on full with max ac, and in my xterra it only got mildly warm while driving. I didn't get a chance to try it at idle but the xterra has air pocket issues in the heater so it would probably blow cold at idle anyways.
Say, did the heater core job involve an AC recharge? Just make up some bullE36 M3 about the AC being a little low on charge before.
yes AC recharge too because you have to pull the dash bar with the hvac case attached to it in order to get to the heater core.
I personally would like to tell the customer to stop being an idiot and, if she wants to use her HEATER, to stop turning the AC on, and if she wants to be cold, use the AC.
Another idea from someone at the shop was to suck all the refrigerant out and leave it like that til they come back in a couple months because their AC isn't cold enough
I'm liking this one.
just an update: the car was a Carmax problem which they shipped off to us. After several days they decided they wanted to just buy the customer out of the car rather than dump any more money into it.
Earlier in the day I was told that a new water pump was approved.
Guess when they told me to NOT do the new waterpump?
yep. directly AFTER I tightened the last bolt holding the new water pump on. This means there was probably 45 minutes to an hour of work leading up to this moment which was entirely pointless.
Anyway, car is gone, I hope they burn it to the ground
