How do you test the heater a/c servo motor on a 98 toyota camary

band damper motors (actuators, servo's regardless type)
you already now the heater core is 180f + hot.
even touching its 2 lines at the fire wall proved that
and OBD2 scans show ECT reads 180F so engine side is good
so then you fail to know the days has what is called heater./distribution air system.
that huge box of damper there that love to fail
even the service manual covers this.
mine even shows removing the damper motor (vac or electr)
and turn the damper hinge rod by hand to prove the damper door is not stuck if not stuck heat flows, hard. to one of many outputs called MODE dampers.
we then test the mode dampers. see why it fails.
all this is under the dash keep the hood closed or go broke throwing part not bad.
the SM service manual on line shows chapter HVAC
and covers every test to do , in all Chrysler products.
oops I see old vacuum servo motors here , actuators modern name

bad controls or bad servo's or even fell off vacuum lines
I see 2 motor servo's too, temperature damper DC motor
and mode, motor drive. called electric inlet actuator.( is Recirc )
and and AUX motor damper drive.
found the hybrid schematic for this car, the whole thing vac and electric.
https://imgur.com/a/cHq4CCY

ONE CAN WATCH EACH DAMPER MOVE OR RUN THEM BY HANDS
AND EASILY PROVE WHICH OF THE 5 FAIL.
SENSE HOT AIR IS ON THE LEFT THERE
WE KNOW KNOW VACUUM SIDE IS BAD, HE DAMPERS, STUCK
THE SERVO BAD, OR THE CONTROL PORTS TO IT ARE BAD.

EVEN A VACUUM LINE FELL OFF OR ROTTED OFF. 23 YEARS OLD

Sound like the blower motor working. Make sure you got raditor fluid filled up and check the thermastat make sure it opens and if that doesnt solve the problem then u got a block heater which need replace.
And check the heater hose to make sure they are hot under the hood

as always, check fuses first.
then scan this car, it will show, mode motor errors. huh?

those are damper. in the heater box.
there are 2 fail points (besides wires)
the control is bad,
or the damper is failing.
The FSM covers this 100%
or at alldata.com

what tech does is makes sure the control sends the signal
the damper (there are 3 types used on all cars)
if its damper motor , the FSM shows the damper tests.
which are unique to Toyota. and a spec, year, 2006.
the mode damper is failing.
the only question is why,
the answer is simple tests. detailed in all FSM of all cars made.

here ill look your up to see which of the 3 type class it is.

your car has a ACC brain, a/c controller, this controller runs the show.
it gets your inputs from the defrost switch and then sends signals
to the mode motor.

FSM quote

Air Vent Mode Control Servo Motor ControlWhen the mode select SW is pushed, the ECU in the A/C control assembly activates the air vent mode control servo motor.
The servo motor rotates to the position (FACE, BI-LEVEL, FOOT, FOOT/DEF, DEF) selected by using the mode select SW,
and moves the damper.
In auto mode, A/C control assembly controls the damper to move to the best position for the conditions without operating the
mode select SW.

I SAY SCAN iT
using any scan tool that suports full Toyota. full scans including
extended factory codes..
i say buy one.
here is one.
http://www.amazon.com/gp/product/B001QIUGVI/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

owning complex cars, and DIY, you need a real scan tool
or just guess.

that is called the MODE damper
its like a door inside the heater box.
there are 3 kinds, (cable. /vacuum and motor controlled)
in a shop we find out
1: which kind then test the control to make sure the control works.
2: then make sure the mode damper works (it wont)
3: we then look and see this car has a motor and the motor is dead
3: we replace the motor and the mode damper now works.

the FSM shows the tests here, under HVAC, you can read that
any time, or login to alldata.com and read that.

if cable , you just watch the cable move. it either does or dont at each end (if fail its obvious why, right>?) jammed or broken cable.

if vacuum, you watch the servo move. if it dont , its bad or the control bad. or the damper is jammmed, i release the link and operate
the door, by hand, it works and i find the servo diaphram leaks
doing a vacuum leak down test, bingo bad servo.

or if electric motor dampers. i do the FSM tests,. no 2 cars
motors work the same, so i'm compelled to RTM read the words
and graphics in the FSM, it shows how to hot wire it and test
ALL angles. if fail the motor is DOA. get a new motor at any toy dealer.
there i have covered all cars made , all 3 systems.
ask questions.

is the cooling fan turning on?is there any leaks?

If you have a floor air vent, then it is likely that you will drop things down the vent ... The first thing that you will need to do is to unscrew the vent cover. ... side holding this into place, so take a suitable screwdriver, and use this to remove all of the .

REMOVAL

1. Disconnect the battery ground cable.
2. Remove the speed control servo. By disconnecting electrical connecter, removeing bolt, and moving servo aside.
3. Remove the coolant/washer reservoir
4. Remove the blower motor.

First, see if it loses fuel, or spark when it dies.

There is a valve on one of the heater hoses that allows heated water to flow through the heater core when you select heat. With heat selected and car warmed up check to see if both of the hoses feel warm. If not then water is not flowing through heater core and valve may need replaced or heater core is stopped up.

Servo motor? I disagree. Actually, there are 3 servo motors in the vehicle; an air inlet servo, an air mix servo, and an air outlet servo. None of which control the temperature.
The AC temp is controlled by a thermister in the cooler box/eveporator unit under the dash.