Ok, I have been desperately trying to find out why my heat will not get as hot as it should in my 93 VG. I have flushed the cooling system, heater core,changed t-stat and bled the system of air with the front end jacked up and the bleeder valve open.One thing that I notice is that if I turn the heat off for a couple of minutes, then turn it on, it gets really hot then starts to blow cooler air. Could this be in the heater control valve? I checked it and the vacuum hoses were disconnected, so I re-connected them, and it has made no diference. I bought this car a few months ago, so I don't know why the vacuum hoses would have been removed. Please help, it's 20 degrees outside. Thanks in advance.

 

make sure the vac lines are correctly hooked up. I think, if they are installed backwards, it can cause weird behavior.
may need to replace them, too, if they are old, and won't stay on.
could also be the vacuum valve is bad, but haven't heard of it.

 

Auto or manual climate control? If it's auto, door motor might be acting up and need to be reset. I'm guessing you have manual though so it could be multiple things, you sure your fresh air vent isn't stuck open and are you sure the vent modes are working properly?

 

It's manual climate control. I checked the vacuum hoses, and compared it to my 91, so I know that they are on correctly.

(I'm guessing you have manual though so it could be multiple things.)

Multiple things as in what? I have my fresh air vent on the left down. Why would it blow hot for about 20 seconds and then get cooler if the fresh air vent is closed?

(are you sure the vent modes are working properly?)
How would I check this?????

Seems that the defrost vents and floor vents seem to blow the coldest.
I pushed the heater control valve in and tied it, and the air never got warm, so I take it that when you push the valve in, it closes that valve. I then untied it, and it blows luke warm, but it should be blasting hot.

 

Ok, I looked in the FSM and saw that my vacumm hoses were switched. I switched them and it helped alittle. I think that I may have air in my heater core. I'm going to bleed the system tonight and check back.

 

I am experiencing similar issues, would you please post the info from the FSM so I can use it? i.e. the appropriate place(s) for the vac lines and perhaps, if there, some ohm measurement specs for the electrical adapters. I need an FSM, sorry to bum, I often rely on this fourm and buy parts instead of knowledge...... Thanks

 

http://www.nicoclub.com/FSM/maxima/1994/

look under the "ha" section

I bled the system for an hour last night with the front jacked up, and got all the air out of the system, and it still doesn't seem to blow as hot as my 91. I'm stumped. What gets me is that if I turn the heat off for a few minutes, then turn it on it gets really hot, but doesn't stay that way. Maybe the heater in the 93 isn't as good as the heater in the 91??????

 

Thanks for the link, I have been lookin for a working one, it's a really large favor indeed.

I just bypassed my control valve assembly, waiting on the engine to cool off more so I can go try bleeding once more on a better hill. There are many to choose from here in limestone country, just got to get there before my thermostat opens and pressure builds!

UPDATE:

I found a good hill, but pressure did build, and my bleeder screw had a little bit of fluid coming out behind it, luckily I was prepared...... Needless to say, I am not 100% sure the system is bled, but I have warm air! It's not the hottest I have felt in a car, and assume another air pocket could contribute to this, and build up perhaps, but it's not cold air like before. So the heat control valve bypass worked for me, even though it was stuck open before........ Maybe my flush job was more helpful than I thought.




Does anyone think this would work as an adequate bleeder since I might be able to set this elbow up where it is higher than anything else in the coolant system?

 

the domain for the pics is blocked at work, but I used one of those prestone flush kits (http://www.google.com/products?q=pre...ed=0CCQQrQQwAg) (available at autozone), on the top heater hose. worked wonders for bleeding my coolant on flat ground.

 

Sorry, Google must be trouble to your work site, but I can't quite wrap my head around the procedure you described in your post whereby using the Prestone Flush Kit on your top heater hose............ How does this bleed out the air possibly trapped in the core?

 

ya install the "t" fitting on the top hose, cap up, as the instructions in the kit say. instead of cracking the bleeder on the intake, you take the cap off, it allows the air to vent at the highest possible point in the system. my heat is so hot, it burns my hands if it's set to blow on the steering wheel where I put my hands (potential for 1st degree burns if I don't move the vents, or turn it down...), once the temp is up.

I also cheated, I grabbed a small funnel, and poured the coolant directly in there. had to shake the hose around, to get it higher, and coax the bubbles out.

 

How in the hell do you have heat that hot? Needless to say I'm jealous. I just don't know what else to do. The 93 heater must suck. Guess I'll just have to live with. N E 1 have any other ideas???

 

That's what I was thinking Ben, but I have discovered as most should, ask as many questions as possible! The fitting I have, shown in the pic you can't see, is an elbow with a small outlet coming off one side, so it is in essence a "T", but with an angle and different sized barbs. I figure, since I can rig it up so that it is the highest outlet for air in the system, that I can most effectively bleed out what little air may be left, b/c after the first two bleedings, and the removal of the heater valve, I now have heat. So maybe a replication of the technique you described, with the set up I have, will produce red knuckles like I want. Tallyho and thanks for the help.

 

well, keep in mind, it takes me 15-20 minutes to warm my car up, idling, since it's been below 30*f here in OKC. until then, i may as well stand in the freezer, with the AC blowing full (BRR!!!!!)

also, your heater core may be blocked, due to corrosion, and whatnot.

 

Just keep trying to bleed out more bubbles, and have you tried the reverse flush with a water hose, or some other kind of pressure like air? That route is bound to be a bit messy, but effective if there is a loose clog. I want to try flushing out the core with either water or air, but don't want to deal with the coolant yet.

 

I will try and bleed it again this weekend. This is my second attempt of bleeding the system. I know I got all the air out last night. I ran it for a freaking hour. I did pull the heater hoses off and ran water through the inlet and outlet and it didn't seem to be clogged. What gets me is that I didn't have to do all of this bleeding on my 91 even after replacing the water pump and the heat got HOT.

 

Just for comparison, I measured the heat from my dash vents.:
1" inside the vent 130*F, 6" from vent 110*F

circumstances:
weather outside 36*F, climate selection on dash only, full heat, fan on high,
engine temp: approx dead center, after 20 minute drive home, and then shut off for about 5 minutes, while I found the thermometer. test took another five, to verify temps.

 

Lucky for u guys that have heat in the max. My heater core is shot, was not expecting it to get so cold down here in South Carolina. I am thinking bout gettin the whole heater control assembly from the Junkyard and throwing it in my car cause its cold brrr!!

 

Just for comparison, I measured the heat from my dash vents.:
1" inside the vent 130*F, 6" from vent 110*F


Man, that is freakin hot. I'm so jealous!!!!!!

 

Man, that is freakin hot. I'm so jealous!!

 

man i just had mines replaced here in north carolina before it started to get cold....my mechanic charged me $180 in labor to remove and replace while no one else in town was near that price...im talkin 500 and above...but i did have my core i had bought from courtesyparts.com lol

 

I have very similar numbers: 68C or 154*F 1 inch inside the top centre vent, with heat and fan on full (auto climate control). I used a laser thermometer after the car was warm, after a 20 min drive, temp. outside was 6C or 42*F.

I did the prestone flush kit and backflushed the heater core also with the attachment (using a garden hose) this past summer. You MUST get all air out of the system. Likely either the heater core is clogged, or you still have some air trapped somewhere in the system.

 

I'm going to park on a hill and jack the car up as high as I can, and see if there is any more air in the system. What's weird is that it blows warm through the vents, but if I switch it to the floor, it barely gets warm at all.

 

Well I was thinking about doing it myself, But with my work schedule, I may not be able to do it in a day or so. The lowest price I got so far to install one was $200, everyone else wanted $400 and above. But since the car is just sitting at the moment i may just experiment on a junkyard car and see how easy or how difficult it is to remove all that stuff.