Cadillac Owners Forum banner

1 - 11 of 11 Posts

·
Registered
Triple Yellow 88 Biarritz, 92 Allante, 05 STS
Joined
·
103 Posts
Discussion Starter #1
Got a 91 Seville, here's the problem, it takes forever for the heater to get warm. It will only start to blow out warm air with the initial temperature hits about 220, that is also when the big coolant hose running from the block to the radiator starts to get warm(thermostat opens???), it is cold until it hits 220 and the cooling fans kick on, if you drive it, it will cool down and not blow out warm air?, any suggestions of what to check?
 

·
Registered
2008 SRX-V8, 1991 Eldorado
Joined
·
1,543 Posts
ht4100 said:
Got a 91 Seville, here's the problem, it takes forever for the heater to get warm. It will only start to blow out warm air with the initial temperature hits about 220, that is also when the big coolant hose running from the block to the radiator starts to get warm(thermostat opens???), it is cold until it hits 220 and the cooling fans kick on, if you drive it, it will cool down and not blow out warm air?, any suggestions of what to check?
I do not replace parts until I am absolutely without a doubt sure the new part will resolve a problem. In your case, I would check first that the damper door is fully actuated during the heat cycle.

You did not mention how long (forever) is, and at what condition the ambient was. A 1991 Seville will not begin the heat cycle until the coolant temperature is at least 160F. If the climate control setting is at ECON + HEAT the A/C compressor should be switched automatically off and air should only be directed to the floor. If any other selection; DEFOG, DEFROST, or HEAT are selceted in AUTO, the A/C compressor will run in conjunction with the heat cycle. If the ambient temperature is well below +50F, the heat cycle will not begin until coolant temperature is above 160F. This could take from a couple minutes to several minutes depending upon the ambient temperature.

If there is little air movement at the foot level when the coolant temperature is +160F, FAN HIGH, I would suspect a partially restricted damper door, or gaps in the duct. If there is adequate air flow at foot level, but little to no heat, I would suspect a problem with the coolant directional control valve (inline on heater hose) or restriced heater core. Note: There is no control "valve" to keep the engine cooling water from flowing through the heater core at coolant temperature above or below 160F, but you are likely not to "feel" any heating benefit until the engine cooling water temperature is at least 160+F. On a very cold morning it will take 100+F degrees to preheat the heater core to +50F. So it is likely you will not "feel" any immediate benefit.

Once the engine coolant reaches 210+F, at least one pulling or pushing fan should come on, as long as climate control is turned OFF. At this time I would feel both the upper and lower hoses to determine if engine cooling water is indeed flowing through them. Both hoses should feel about the same temperature (hot) once a fan kicks on. If a cooling fan comes on and the upper radiator hose is much cooler than the lower, I would suspect the thermostat is not responding to design.

Hope this helps.
 

·
Registered
Triple Yellow 88 Biarritz, 92 Allante, 05 STS
Joined
·
103 Posts
Discussion Starter #4
I shouldn't have said forever, what I mean't to say it that it doesn't blow out warm air until the temp hits 220 or so and the engine cooling fans kick on. Then it will blow warm air out for a minute or two then get cooler, There seems to be enough air blowing out of the vents. I took the "valve" off that's inline with the heater hoses, but cracked one of the plastic ends so I had to order a new one, I'll put this on and see if I can get lucky, The hose from the block to the radiator(on drivers side of car stays cool until 220) the one on the other side gets warm.

The valve I took apart and am replacing(since I cracked it) has 3 ports and is located just behind & below the rear valve cover.

Thanks for the help
 

·
Registered
2008 SRX-V8, 1991 Eldorado
Joined
·
1,543 Posts
ht4100 said:
I shouldn't have said forever, what I mean't to say it that it doesn't blow out warm air until the temp hits 220 or so and the engine cooling fans kick on. Then it will blow warm air out for a minute or two then get cooler, There seems to be enough air blowing out of the vents. I took the "valve" off that's inline with the heater hoses, but cracked one of the plastic ends so I had to order a new one, I'll put this on and see if I can get lucky, The hose from the block to the radiator(on drivers side of car stays cool until 220) the one on the other side gets warm.

The valve I took apart and am replacing(since I cracked it) has 3 ports and is located just behind & below the rear valve cover.

Thanks for the help
You are welcome but, .... it is not a true "Valve", it is directional flow device much like a check. Be absolutey sure the arrow points in the proper direction upon installation of the new part. I would suspect your heater core may have a lot of sediment inside. Once the heater hoses are off, try flushing it with a garden hose from one direction, then the other. (alternate supply and return heater hoses) keep doing this until the water runs clear from the core.

Try the other suggestions for determining proper passage of water through your system. If you have good flow, good strong air supply, either the damper is not fully opening or the core is plugged.
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,792 Posts
Be sure the "T" you replace it with has a restrictor in one leg just like the original.
 

·
Registered
Triple Yellow 88 Biarritz, 92 Allante, 05 STS
Joined
·
103 Posts
Discussion Starter #7
ok, replaced the "T" intersection in the line, and still it only blows out luke-warm air for about 10-20 seconds, then gets cold, if you turn off the heater for a minute or two, it will blow out luke-warm air for 10-20 seconds, and get cold again.

I removed the liner for the glove box and checked to make sure the door is moving, I checked it by using the CC Unit(60-90 degrees) it moves like it is supposed too, I even disconnected the rod to make sure that it is fully on the hot side, and it still has the same problem. so we can rule that out.

I my 85 olds regency had this same problem, I replaced the heater core, and it still worked like it did before, no difference.

I find it odd that the coolant hose from the block to the radiator stays cold until the cooling fans kick on at 220, maybe the T-stat isn't opening correctly??,

I replaced the radiator a few months ago, and the coolant is still relatively green(and, yes I added GM coolant tabs!) looking at the coolant, it doesn't appear that the coolant has sediment in it,

So I think I'm gonna replace the T-stat, only 7 bucks anyways. Is there anything else that could restrict flow in these cars?
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,792 Posts
ht4100 said:
I find it odd that the coolant hose from the block to the radiator stays cold until the cooling fans kick on at 220, maybe the T-stat isn't opening correctly??,
That's why I said replace the thermostat.
 

·
Registered
Triple Yellow 88 Biarritz, 92 Allante, 05 STS
Joined
·
103 Posts
Discussion Starter #9
Replaced the T-stat, and "T" intersection valve and let the car warm up. It still doesn't blow out warm air, Like I said I checked the door inside the glove box(Hot & cold door) and made sure that it worked, is this the damper door you are talking about?
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,792 Posts
Yeah, that's most likely it but be sure you are looking at the air mix door as opposed to an air distribution door. Make sure it has vacuum to it or it will not operate.

Have you flushed the4 heater core?
 

·
Registered
Triple Yellow 88 Biarritz, 92 Allante, 05 STS
Joined
·
103 Posts
Discussion Starter #11
Hey, just wanted to let you guys know that I had the heater core flushed and the heat works perfectly!!, I ended up selling it for 3000 1 hour after I picked it up from being flushed, Thanks!
 
1 - 11 of 11 Posts
Top