evaporator temp probe

How important is the placement of the evaporator temp probe in the
evaporator? Can the misplacement cause a vent temp problems?
History is my 1998 Caravan 3.3 had the evaporator replaced earlier
this month and I have always been able to get 45deg in rec. mode,Now
the lowest it will go is 53deg and I have to use the fastest fan speed.
If I use my normal second fan speed it will raise to 60deg.
Have been back to the chrysler dealer 3 times now and they continue to
tell me pressures are normal. What are they missing?

Thanks for any help
JohnR

 

If it's too far in, vent temps won't be low enough. If it's too far out,
the evaporator can ice up, eventually causing loss of vent airflow.

Not normal. Slower fan speed = less airflow across evaporator = more time
for air cooldown = colder vent temps. Higher fan speed = more airflow
across evaporator = less time for air cooldown = warmer vent temps.

Pressures have little to do with this -- sounds like something was not
done correctly on the evaporator R&R. Mode doors not going all the way
where they're supposed to, clutch cycling switch temp probe improperly
installed, etc. They keep telling you "the pressures are normal" because
they really don't want to tear the dash back apart to fix their screwup.

Um...why are you letting a dealer service department screw you, now that
your vehicle's out of warranty?

 

Sure let Daniel give you false info again, The probe on the vehicle has to
go all the way in untill it stops, thats the way it is designed The new
evaporator that was installed has a hole set up for the probe to be
inserted.

And Mr Stern should know by now that pressures have alot to do with proper
effiency, To low and to high of pressures will cause lack of cool air.

You dont say what the ambient temperature is where you are from and that
could have an effect on evap temp also, this chart is for your vehicle

Glenn Beasley
Chrysler Tech


A/C PERFORMANCE TEMPERATURES
AMBIENT TEMPERATURE 21°C (70°F) 26.5°C (80°F) 32°C(90°F) 37°C (100°F)
43°C (110°F)
AIR TEMPERATURE AT LEFT CENTER PANEL OUTLET 1-8°C (34-46°F) 3-9°C
(37-49°F) 4-10°C (39-50°F) 6-11°C (43-52°F) 7-18°C (45-65°F)
COMPRESSOR DISCHARGE PRESSURE AFTER THE FILTER DRIER 1034-1724
kPa(150-250 PSI) 1517-2275 kPa(220-330 PSI) 1999-2620 kPa(290-380 PSI)
2068-2965 kPa(300-430 PSI) 2275-3421 kPa(330-496 PSI)
EVAPORATOR SUCTION PRESSURE 103-207 kPa(15-30 PSI) 117-221 kPa(17-32
psi) 138-241 kPa(20-35 PSI) 172-269 kPa(25-39 PSI) 207-345 kPa(30-50 PSI)

 

Thanks for the reply guys.
heres more info
The vent temps I quote are both on 95deg days and 70deg nights
the only difference is that during the day it takes much longer to cool
because of all that glass in the van. The fan speed it still true fan
speed high ,vent temp gets to 53deg turn it to second speed and the
vent temp starts to go up after 15 minutes its at 60deg. I pinched off
both heater hoses to the heater core no difference and when I push the
rec. mode button I hear door close with increase in air movement noise.
the question of the placement of the probe is that I asked for the
parts back and on the old evap. I can see where it was supposed to be
from the factory.
It just so happens that on my van getting to the temp probe is pretty
easy to see and it is not in the same position as the original. it is
now much closer to the bottom of the evap. as evap. would sit in an
installed position.

Glenn those pressures you list are much higher than the 2.2 Times the
ambient temp. that I've heard about. what gives? does this Caravan need
higher liquid line pressure to operate correctly. are you saying that
my high side should be 290-380 PSI on high side at 90deg?

 

Glenn is giving you his usual halfassed information...parts of it are
almost correct, but he's looking in the wrong direction. If your mode
doors are not operating properly, it's entirely possible to see acceptable
pressures on the high and low side but still have unacceptable air temp at
the vent. Likewise, if the temp probe is improperly installed (and yes,
both "not far enough in" and "too far in" are possible), pressures will
still remain largely normal. Grossly improper pressures will be evident
only if there is a serious airflow blockage across the evaporator or
condenser, or if there is a problem within the A/C plumbing (blockage,
faulty condenser, faulty expansion valve, moisture in the system,
noncondensibles in system, excess oil, under- or overcharge).

That's a good place to start, then. But really, I don't see where *you*
need to be worrying about this overly much. Take the van back to the
service department, and do not be satisfied with their irrelevant "the
pressures are normal" answer. The vent temps are NOT normal -- they are
not cold enough -- and since they WERE cold enough before you brought the
van in, it's up to them to find and fix their screwup.

Perhaps you'll get "lucky" enough to visit the stealership where Glenn
"works".

See above: Usual halfassed response from Glenn.

 

Daniel they say it's in spec. I say it not cold enough. They've have
the car 3 times and it comes back the same. They have my money. I just
think, as Glenn says something is wrong and now that he has provided me
a temp/ pressure chart from Chrysler I can ask them to use it to
recharge my van. Who knows how they're recharging it, if they even are.
By weight or just 2.2 times ambient temp.Its just that the Chrysler
chart says high side should be 290-380 psi @ 90deg much higher then
I've read it should be 198/207 psi @90 .Why is Chrysler so much higher?

 

Your system has a feature that will calibrate itself, If the doors were out
of positon it will reset them to specs. If the door cannot be reset it will
generate a fault code at the panel, I think Mr Stern Thinks we are working
on a Dodge Shadow or an Acclaim. you can do this test yourself, im sure the
dealer already did it, or hope they would have
CALIBRATION/DIAGNOSTICS TEST ENTRY
TO INITIATE TESTS:
a.. Set Blower motor ON HIGH
b.. Set Mode position to Panel
c.. Open all A/C outlets
d.. Set Temperature to Cold (Both slide pots if equipped)
e.. Depress WASH and REAR WIPER button simultaneously for 5 Seconds (Until
all LED's light)
RESULTS:
a.. All LED's will turn on for 5 Seconds
b.. Calibration Test is running when REAR WIPER and INTERMITTENT are
alternately flashing. Cooldown test is running if A/C and RECIRC are
alternately flashing.
c.. Acceptable results is REAR WIPER LED is the only LED flashing. Push
Rear Wiper to exit.
d.. After all tests have passed, Calibration Diagnostics and Cooldown can
be run separately.
COOLDOWN TEST ENTRY
TO INITIATE TESTS:
a.. Set Blower motor ON HIGH
b.. Set Mode position to Panel
c.. Open all A/C outlets
d.. Set Temperature to Cold (Both slide pots if equipped)
e.. Depress WASH and A/C simultaneously for 5 Seconds
NOTE: Prior to start of test, If the evaporator is already cold, the system
will fail test. To correct, operate system with A/C OFF and the blower motor
ON high for three minutes prior to starting test.

RESULTS:
a.. All LED's will turn on for 5 Seconds
a.. Cooldown Test is running when A/C and RECIRC. are alternately flashing.
If A/C and RECIRC. are flashing simultaneously, Cooldown has failed.

 

Glenn I ran the recalibrate procedure no errors returned
Is that chart you posted correct that I should be 290-380 psi @ 90deg.
Why so high?
Do you think the tech would have used recharge by freon weight ,the
pressure/temp chart or just 2.2 times ambient temp. refill procedure. I
feel personally that it was 2.2 times way, that would explain why my
vent temps are higher and it takes so long to get cool.not enough
freon. do all chrysler products use that same chart or only Caravan?

 

Don't just accept "it's in spec". Escalate the matter. The A/C was
performing better before you brought it in -- you need to emphasize that
to them.

Typical dealer "service".

The chart Glenn provided you is contained within service literature the
dealer has. If they're choosing not to use it -- which is quite possible
-- you stand little hope of changing their mind by telling them to do so.

Perhaps you are reading information applicable to older R12 systems, which
run at lower pressures, or you're simply reading inaccurate information.
High side pressure of 198/207 at 90F would be low.

 

Daniel I've been to this site
http://www.acsource.net/acforum/viewforum.php?f=1
and their previous site
http://www.aircondition.com/wwwboard/
thats where the 2.2 times ambiant temp comes

 

Better-quality info at the forums on www.ackits.com

 

That chart is from the 98 manual. If your system is overcharged or under
charged you will get this problem, If you arent happy with it, tell them
to recover it and weight it, then recharge again. I would bet it will get
colder

Glenn

 

naw, either too much charge or 5 ounces low

 

dan just so you know when a evap.coil has been replaced in a mini van the
havc head has to be recalibrated once it is bac together so a cool down test
will run and finish
if the cooldown test fails it is because the door travels are off and the
sytem will not work meaning all the leds on the control head flash and won't
stop untill the the fault is repaired so if has to be a charge issue since the
poster made no mention of flashinfg led's

 

if the evap coil was leaking there was no way it was preforming better before
since it was low on a charge

 

Oh, look, it's another of Glenn Beasley's sock puppets.

*yawn*

 

Tim I know how the a/c was proforming because I have owned it since new
and I keep a thermometer in the center vent 45deg since new.
I have learned reading these forums that one of the first signs of a
low charge is a loud hissing noise from where evaporator is, it's
expansion valve noise. and I did have that symptom a few day's just
prior to it having trouble getting to 60deg thats when I known I had
problems. still I need to know if 290-380 psi @90 is proper high side
psi. The chart that Glenn posted says yes but everyone else says its
too high.

 

it's a real shame that a smart man like you can only think with your ego instead of
your intelligence what a waste

 

the chart glenn has is a page right out of the service manual

 

Its not ego, just trying to put the facts out because you Tim sound
exactly like the people at the dealership. Lots of talk no action and
no help on trying to solve my problem so just stop responding to this
thread.