Heater is intermittant 1991 Lesabre touch panel

Heater is more likely to start with engine start than when button is pressed. It operates part of the time. Heated water is passing through the core. Can't locate relay, if any or ballast resister. Fuse also does not appear to be labeled for heater. 3.8L.

Not quite clear on your problem. Do you have no temp control? Is the fan not working? Are any of the controls on the control panel working? A little more detail please.

do you have dual zone climate control or manual heat is the blower working .some thing to look at if blowers not working then it's the resistor or the blower motor they are .located under the hood under the eletrical cover by fire wall right in the middle. to the left of blower is the resistor .other thing to look at if it's climate control dual zone .behind the glove box is a eletric blend door actator they have troubles going bad cracks in the gears you can watch that working if you drive the car. some troubles start car have heat then go's cold or cycle heat from hot to cold then it starts working again .this is a blend door trouble.give us more detals i hope some of this was helpful

A little confusing.....what is your problem? Heat or airflow?

Do you have auto temp? Auto temp with vary airflow based on the setting you have and what the actual temp of the air is....for example, suppose you get in the vehicle and your engine is warm from running, but has been shut off a few minutes and the interior temp is low.....if you start the car, and the auto temp is set high, the blower will run at high speed, and then slow down and almost stop as the set temp is reached....this is how the blower operates on auto temp....if you switch it over to manual, the blower will run at the speed you set, no matter how warm it gets....

Now, if the problem is heat, could be a temp door, contol head, actuator, or heater core problem....

To Clarify. Car has Autotemp. Blower will work part of the time. Will not work when needed most of the time, even with manual. When it does run on auto or on manual it will run for several minutes and then shut off even when the interior air temp is below the set temp. Dampers appear to be operating. As I mentioned in the original post, I cannot locate the ballast, the relay or a labeled fuse for the heater. I have tried swapping the relays with no change. I'm wondering if the shut off occurs as the control starts to lower the fan speed(bad resistors). Does the system have both a relay and a resistor and where are they? Chilton show a resistor. Can't find it. There are relays on the under hood panel, but none labeled heater. Thanks guys for the help.

I believe there is a blower control module under the hood around the top of the evap case, they were troublesome.

Normally, when the blower motor control module fails, either it will cause the fan to run on high speed (even with ignition OFF), or not run at all. However, the fact that you have an intermittent problem, does not necessarily rule out a potential problem with the module. The fan motor could also be the culprit.

As Max mentioned, the module is located on top of the Evap/Fan box and under the fuse/relay panel mounted on the firewall. There are two studs holding the fuse/relay panel with 2-nuts to secure. You will need a 10mm deep-well socket to remove the nuts (preferably with magnet insert to keep from dropping the nuts.) Once the nuts are removed, simply slide the fuse/relay panel forward to expose the blower module underneath. Remove the two terminals & three screws to remove the module. Since you have an intermittent problem, I would pay close attention to the condition of the wiring & terminals connected to the module. BTW, there is not a separate relay/fuse/resistor, for the Auto Temp Control, the module is a self contained unit. Below is an example of the module and a source available to purchase a new unit. If you can find a used module from one of the following cars @ eBay, pick & pull or JY, you could save some $$.

Note: The module for an 1991 LeSabre has a 4-pin 2-pin connection. Some LeSabre & PA's (different years) use a 3-pin 2-pin connector, so be careful if buying used.

BUICKELECTRA(1985 - 1990)
BUICKESTATE WAGON1989
BUICKLESABRE(1986 - 1991)
BUICKPARK AVENUE(1991 - 1993)
BUICKREATTA(1988 - 1991)
BUICKRIVIERA(1986 - 1991)
CADILLAC60 SPECIAL1993
CADILLACALLANTE(1987 - 1991)
CADILLACCOMMERCIAL CHASSIS1992
CADILLACDEVILLE(1985 - 1993)
CADILLACELDORADO(1986 - 1991)
CADILLACFLEETWOOD(1985 - 1992)
CADILLACSEVILLE(1986 - 1991)
CHEVROLETCORVETTE(1986 - 1989)
OLDSMOBILE98(1986 - 1993)
OLDSMOBILEDELTA 88(1986 - 1991)
OLDSMOBILETORONADO(1986 - 1991)
PONTIACBONNEVILLE(1988 - 1991)

RockAuto Parts Catalog (http://www.rockauto.com/catalog/raframecatalog.php)

ACDELCO Part # 15-72530 {#12484912}
MODULE,BLO MOT CONT 4 PIN/2 PIN CONN $128.79

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