1990 740 GL - No air from blower, with any setting

  • Thread starter Thread starter Charlie
  • Start date Start date
Yea, there is a small oval panel with a electrical connector on it.
The back of this panel has three coils that get REAL HOT and are
inserted into the heaterbox. Some sort of preheater? It is screwed to
the Heater box between the blower motor and what I believe is the AC
evaporator. When removed, I can see the blower 'wheel' on the
right, and the evaporator? on the left.

With this panel off there is a good deal of air flow. (Out the hole
that the panel was covering) So I suspect the blower is functioning
properly, but as blurp said a little earlier, the air may not be
passing through the evaporator, or whatever is on the other side of
that. It would seem possible since that is the only direction for
the flow to go. More investigating is order I guess.
Click to expand...

That's the resistor for the lower speeds of the blower motor, it is
cooled by the airflow, so if you run the blower with that removed from
the hole, run it on the highest speed only which doesn't use the resistor.

Yes as I recall the airflow comes from the motor on the right, and
passes through the evaporator on the left. You may in fact have a
clogged up evaporator or heater core. Did the problem come suddenly
though or did you acquire the car like this?
 
That's the resistor for the lower speeds of the blower motor, it is
cooled by the airflow, so if you run the blower with that removed from
the hole, run it on the highest speed only which doesn't use the resistor.
Click to expand...
Ah. I learned some thing, cool... I do electronics, I did not
recognize it as a resistor but yea, I guess it would do that.
Yes as I recall the airflow comes from the motor on the right, and
passes through the evaporator on the left. You may in fact have a
clogged up evaporator or heater core. Did the problem come suddenly
though or did you acquire the car like this?
Click to expand...

Unfortunately I acquired the car like this. So I don't know if
this was quick or got worse over time.

From receipts left in the car, I get the feeling it sat for awhile.
One of the more recent ones (9 months old) was for a Volvo dealer to
'Get running' and test driver side heat. The work they did
according to this receipt was a basic tuneup. They reported no
problem found with the heat.

The AC looks to have been disconnected long ago, judging by the rust
and grime covering the AC compressor. (and the lack of a belt)

Thanks for the help,
Charlie
 
Unfortunately I acquired the car like this. So I don't know if
this was quick or got worse over time.

From receipts left in the car, I get the feeling it sat for awhile.
One of the more recent ones (9 months old) was for a Volvo dealer to
'Get running' and test driver side heat. The work they did
according to this receipt was a basic tuneup. They reported no
problem found with the heat.

The AC looks to have been disconnected long ago, judging by the rust
and grime covering the AC compressor. (and the lack of a belt)

Thanks for the help,
Charlie
Click to expand...


You might just have to tear the whole dash apart and dig into the heater
box, it's not too bad on a 240 but I've never pulled that much apart on
a 740. I don't know if there are other ways to access the heater core
and evaporator, but on the plus side, it's a good opportunity to fix the
AC, it's a pretty simple system with only a few major components and if
nothing else it makes a dramatic improvement in how well the winshield
defroster works.

I recommend picking up a Haynes manual for the 700 series.
 
You might just have to tear the whole dash apart and dig into the heater
box, it's not too bad on a 240 but I've never pulled that much apart on
a 740. I don't know if there are other ways to access the heater core
and evaporator, but on the plus side, it's a good opportunity to fix the
AC, it's a pretty simple system with only a few major components and if
nothing else it makes a dramatic improvement in how well the winshield
defroster works.
Click to expand...
Yup, good thing I have a long weekend ahead.
I recommend picking up a Haynes manual for the 700 series.
Click to expand...

They do not seem to have a Haynes for the 1990 740. Only go to 1988
on the web site.

The owners manual gives the info for getting service manuals from
Volvo. It lists them available as individual chapters, sections or a
complete set. Any idea if these still exist or are worth it?
 
The owners manual gives the info for getting service manuals from
Volvo. It lists them available as individual chapters, sections or a
complete set. Any idea if these still exist or are worth it?
Click to expand...

Does '90 have the new style dash? I don't remember when the 740 got that
update.

The green books are excellent, I don't know if Volvo still sells them,
but they turn up on Ebay from time to time, and I recently saw a
complete set for the 740 on Craigslist, but the Haynes manual covers my
'87 and has been adequate so I didn't buy them.
 
Does '90 have the new style dash? I don't remember when the 740 got that
update.
Click to expand...
I have an 85 and a 90 and are the same. Or at least outwardly.

jimB
 
jimb said:
I have an 85 and a 90 and are the same. Or at least outwardly.

jimB
Click to expand...


Cool, then the Haynes manual will cover the '90, it was just published
prior to that. The 760 got the dash and exterior cosmetic update sooner
than the 740, it has substantial differences and more closely resembles
the 940 and 850 dash.
 
Well after an afternoon with a 2 foot section of 5/8 heater hose
connected to the shop vac. A 4 foot section of fish tank air line
tubing connected to an air gun(Use this with care! It will flip around
like crazy.) I've blown and/or sucked all the vents possible, The
air flows great now. Sweet.
 
Charlie said:
Well after an afternoon with a 2 foot section of 5/8 heater hose
connected to the shop vac. A 4 foot section of fish tank air line
tubing connected to an air gun(Use this with care! It will flip around
like crazy.) I've blown and/or sucked all the vents possible, The
air flows great now. Sweet.
Click to expand...


Hey, that's a great idea. Any idea what it was so clogged up with?
 
Hey, that's a great idea. Any idea what it was so clogged up with?
Click to expand...

Believe it or not, I won't rule out that the blower motor could have
been plugged in backward. As suggested by Ken earlier. But if so
that was only a contributing factor. (I dropped it to the car floor,
unplugging it from the connector, when removing, so I was unable to
determine if that was the issue.)

I was running the blower with a jumper wire so I could simply
reverse it. Was getting no effect until I vac'ed out the area
between the blower and the evaporator by going through the resistor
plate hole with a length of heater hose. I got some pine needles, but
not what I would consider enough to block it. However at this point
I noticed a improvement! So I attacked all the vents with a blow gun
and a section of air tubing. I got quite covered with dust and dirt
at this time. With each vent I blew air into, the overall flow
improved.

So... I'm going with a (possibly) backward wired blower, with a
'stuck' internal flapper, caused by 18 years of dirt and other
buildup.
 
Charlie said:
Believe it or not, I won't rule out that the blower motor could have
been plugged in backward. As suggested by Ken earlier. But if so
that was only a contributing factor. (I dropped it to the car floor,
unplugging it from the connector, when removing, so I was unable to
determine if that was the issue.)

I was running the blower with a jumper wire so I could simply
reverse it. Was getting no effect until I vac'ed out the area
between the blower and the evaporator by going through the resistor
plate hole with a length of heater hose. I got some pine needles, but
not what I would consider enough to block it. However at this point
I noticed a improvement! So I attacked all the vents with a blow gun
and a section of air tubing. I got quite covered with dust and dirt
at this time. With each vent I blew air into, the overall flow
improved.

So... I'm going with a (possibly) backward wired blower, with a
'stuck' internal flapper, caused by 18 years of dirt and other
buildup.
Click to expand...
Glad you're making progress, and it sounds like you had a bit of grubby
fun as well :-)

I've only just, very belatedly realised that 'a picture is worth a
thousand words', so on this web page
http://camyork.trustpass.alibaba.com/product/10031917/Fan_Wheel_Impellers_Centrifugal_Impellers.html
is a picture of a similar centrifugal fan basket, it's correct direction
of rotation due to the blade alignments, is clockwise. This info ought
to help you establish if yours is running correctly.

Apologies for being so dumb as to not be able to figure out how to get
you this info, before you had the thing in bits for the second time.

Best wishes,
Ken P.
 
Charlie said:
Believe it or not, I won't rule out that the blower motor could have
been plugged in backward. As suggested by Ken earlier. But if so
that was only a contributing factor. (I dropped it to the car floor,
unplugging it from the connector, when removing, so I was unable to
determine if that was the issue.)

I was running the blower with a jumper wire so I could simply
reverse it. Was getting no effect until I vac'ed out the area
between the blower and the evaporator by going through the resistor
plate hole with a length of heater hose. I got some pine needles, but
not what I would consider enough to block it. However at this point
I noticed a improvement! So I attacked all the vents with a blow gun
and a section of air tubing. I got quite covered with dust and dirt
at this time. With each vent I blew air into, the overall flow
improved.

So... I'm going with a (possibly) backward wired blower, with a
'stuck' internal flapper, caused by 18 years of dirt and other
buildup.
Click to expand...


Well either way you got it going. I love the feeling of accomplishment
every time you turn on something like this later and it still works.
 
Thanks to all who took the time to consider my problem and provide
their input and experience. It all helped in one way or another.

Now to find out why the underside of the trunk carpet gets so wet.
(But I'll start a new thread for that, if it comes to it)

Thanks again.

Charlie
 
Charlie said:
Thanks to all who took the time to consider my problem and provide
their input and experience. It all helped in one way or another.

Now to find out why the underside of the trunk carpet gets so wet.
(But I'll start a new thread for that, if it comes to it)

Thanks again.

Charlie
Click to expand...


Been there, done that. Look at the taillights, particularly the foam
gaskets around them.
 
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