ac relay testing

[Acefrehleyspik]

Hi, I have a 92 Tracker with AC that has relay problems, I went direct to power to check the compressor and the condensor blower and as soon as I put the juice to them they ran perfectly, I have power at both main input red wires but it doesn't make it thru the relay to power up these components, obviously the 25a fuse is OK or I wouldn't have juice at the red terminals. I find it funny that both these identical relays would blow at the same time but, as I live in an area where I use AC about 2 weeks a year I hadn't tried it since I bought it and converted it from 2wd to 4. I may have shorted a wire when I did the conversion, who knows? The lady that owned it told me the AC worked perfectly and as she was the secretary for a chevy dealership owner everything on the truck had been given the cadillac treatment so I had no reason to doubt her. Does anybody have an easy check method for these relay's? I would really appreciate it, thanks, Mike

[fixkick]

the AMP controls these relays.
the AMP is really just a A/C protection and engine protection logic box. (rules)
1992. clutch drops out, ok, that is normal but not if full time, the clutch drops even when the evap core is too cold... by design.
the red wire is hot all the time.s (if not fuse blown)
blow at the same time ( deEnergize both at same time?)
both relays are dropped any time the hi/low switch sees and error in pressures. (high or low both)
if the hi/low is happy, then only the AMP can drop them both.
the Hi/low is hot all the time from blower power. fuse.
so the hi/low must be 12vdc at all times. all the time. both sides or you have a loop issue, (pressures wrong)

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in all cases. we find out :?
1: is the amp dropping the clutch.
2: or is the hi/low loop switch dropping.

just 1 reading tells me that.
the yellow wire. if that drops its a loop problem
if either wire pink (relay) or blue-red fail to hold 0v. then the amp is dropping out the relays, 1 or both.

if the amp is doing this dirty work. then we check its inputs, its just a logic box(CPU?) and will drop for many reasons, all by design.
drops for.
1: engine over load.
2: engine overheat or the switch lies. or wires to it cut.
3: evap core iced up.
4: blower dead.
5: thinks your are cranking all the time, would take 2 fails here, cut wire and shorted to 12v... hardly likely

each can be checked with a meter, if need be. forget that until you prove 2 wires above colors, are going to 12vdc. (failed)

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the engine tells the A/C to drop out on engine overload, or passing (wide open throttle mostly)
im sure that is not happening.

[Acefrehleyspik]

I've got 12 volts to the green wire at the dual switch and nothing (.2) at the yellow. , by the way when I look into the sight glass what exactly should I see (running and not running) this one is clear and no one has said if a colour should be there or what?

[fixkick]

the switch is open, its cutting out everything... output zero, 12vdc id good, or what ever battery reads now. its just pressure switch, that is all.
1 its bad
2 the pressure is too high
3 the pressure is too low.
only 3 possibles.


glass.
Check the Site Glass

"Many receiver driers have a site glass on the top.
small window allows a view of the refrigerant moving through the lines.
With the system running, there should be no bubbles in the lines.
If there are bubbles, this indicates refrigerant levels are low, in which case there may be a leak in the system.
Oil streaks and froth in the lines also indicates that refrigerant levels are low,
while a milky fluid indicates the receiver drier is leaking desiccant, according to the Pro Car Care Website.

Note that when the system is off, some bubbles may be visible in the lines. This is perfectly normal, and not an indication of low refrigerant levels."



the hi/low switch protects the compressor , for both bad conditions, low freon, and too much.
the 2 pressures are stated in the fSM
they are:
30 psi OR over 382 PSI. (95' it is, 28 and 455 psi) the newer cars 1995+ are R134a...

are you running R134? in the 1992 is not set up for R134.
and this 1992 orig. switch is just that, set for R12. levels.

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the only way to tell is to use manifold gauge set. but that wont fit old R12 system.
the the right tool, you can see if the switch i working or its telling the truth, and cutting out for right causes.

[Acefrehleyspik]

I went through every test that you listed on the fixkick site, I bought the truck and did not run the AC because it was through the winter so, no need , all I had was a verbal yes, the AC works perfectly, and the lady worked for a GM dealership so , I assume it did work, when I look in the site glass it looks empty, there is no colour. stains, bubbles or anything, it is the first older Tracker I have worked on with AC, there just are very few here so I don't know what I should be seeing. The AC Amp has 9 wires to it , it is a 9/91 Cami built 2dr, that was from Florida that was re-imported to Canada in 2000 but has all US required parts, I had to change the speedo to a kilometer type to pass legal requirements, also it has a US Federal std. trans ECM , it was a 2 wheel drive but I converted it to 4wd. Thought some of this might help.

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Just as a follow up, it is R12.....1.43lb. charge., Wal-mart here sells one that is compatible with R12 that you just hook up to the schrader valve.

[fixkick]

the running sight glass is only one thing, if bubbles show running, its not all the important.
what matters is why the hi/low is tripped.
nothing else. (well if not leaking)
wow you found R12, never seen that in ages... its only sold used, reclaimed here and is like $75 a pound, and rising (punitive taxes)
well great, you a are running spec, refrigerant... great.
well if you over charged it , it will trip.
why not go to and AC shop, and get them to check it with the 2 gage manifold.
then look at the 1991 to 1994 FSM charts for matching (setting) pressure to (outdoor temperature and humidity).. this is the last step in all AC work, getting it right. per the chart.

here is the wrong chart, i dont have the R12 chart.
but shows you how it works.

http://www.fixkick.com/AirCond/r134-1996-chart1w.jpg

the amp has nothing to do with the Hi/low switch, the amp can not command AC "ON", if the Hi/low cuts all power to the relays, ( it wins, and saves the compressor to boot.)
the hi/lo is a fail safe. device.
nothing else matters.
is the switch fibbing or not?, the only way to tell is use the gauges.
my guess is its overcharged,
my wife's car , right now, at ambient 50% hum. + 90F is running 40PSI on the low side. R134a. V6 engine, and does not trip.
sorry i dont have the R12 data.

id get help at an AC shop this is old hat to them.... ,
i just had to buy R22 from my home, dont ask how much, (a fortune) it to is illegal now and taxed to ying-yang.

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are you sure its real R12? and not propane or other gasses sold as R12,? (here in usa, there a many hacked R12 clones, and very hard to setup)

whats your low side pressure? running it. with high low bypassed say for 15seconds. (bypass for only short time, and only if you know there is
a full pound in the system.

the samurai spec. i have
ran 18oz . (1993 for example)
the pre 134a ran 21 oz. on sidekicks/trackers/vitaras of same breed.

start with 18 oz and work up.? to 21 oz,
and the generic formula.
Ambient temp X 2.2 = high side pressure
so here is 90f, x2.2 and would be 198psi on the high side.

the correct amount listed on some pages is 21 oz. of R12. (before R134 changed it)
so put in the R12 , from total vacuum. say 15oz, (about)
then as you near the 28psi the HI/log closes. and the clutch pulls in and compressor wakes up.
then use the charts. to top off...
that is what the charts are for , the fine tuning.

only other way is :
on the generic sites (a/c.) you most know the total volume of the system to do their math, and that is not known.
the 21 oz. is by weight, not volume of r12 can. yes, tricky and is sold commercially by weight. in fact the jokers scaled my F22 can before and after i was charged up)
liquid gold here it is.....

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be very sure the system has say at least 15oz of R12 and oil to spec.
before hot wiring (jumping) the hi/low switch.
and do so for short time. just long enough to glance at gauge.
or set up, start engine.
and jump it. 15seconds.
got 20 or more PSI? on the low side. if not?, cut the jump and add more... repeat.
you need the over 30psi for the Hi/low to hold in, then when it does, the compressor runs by self. (amp happy? sure)
then top of fto the charts. (using your local radio station temp and humidity , live)
or this.
http://www.wunderground.com

type in your town and bingo, local ambient.

good luck !!!

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keep in mind the system hates water, in the loop,
the vacuum pull , gets out all water, and air is full of it.

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im no loop expert. (i can only tell you why the logic fails or why the hi/low fails. tuning the loop takes, serious art now, and skill.... due to.....
and with the reclaimed R12, gee what do you get with reclaimed, well, some R12, propane, some R134 and god knows what.?

and just where are the tables for R12, "who knows what" , same answer , nobody knows... call it R(HKW) or R666 ?
crossing fingers that your Canada R12 is pure, from Dow Chem.

[Acefrehleyspik]

The only places here that do auto AC are the dealerships, $125/hr, I actually didn't know anyone with AC until the mid 70's (my dad) and we NEVER used it, only was about 2 weeks a year it was hot enough to use it BUT the last 3 or 4 years are a different story (global warming....yep) it was 33 Celsius here today and hit 40 a few times last year (I still don't know metric, but it was HOT!) so anyway the guy I get my R12 from "vampires" it from systems he is discharging because he can't get rid of it so it is/was cheap...... no one would take it!.......he runs a rad shop. He charged me $25.00 to leak test and refill it on my daughters car a couple years ago, not sure about now. What do you check the pressure with? A good tire gauge? Dumb question but I really don't have any experience with AC.[/align]

[fixkick]

yes, if you go to a store here, any store, (auto) or even walmart, all there is is the R134a. (with dye, with out, with oil,l with out. etc)
no R12. and for sure no support for it, gauges and what not...

so you can't buy the fill "can" and hose with cheap plastic, low-side meter. not here. for R12.
only used tools, .
below:
this is what fits now. or (imports below) assumes it fits your fill tank, that too many need and adapter.

http://www.ebay.com/sch/i.html?_from=R40...e&_sacat=0

the purpose of Freon, was to have a refrigerant that does not burn (Propane works but is not safe, for sure in a crash)
and not toxic, the best refrigerant at the time is Ammonium gas, pure. and is very toxic to persons, directly. at this pure level.
at 300 parts per million (ppm) is immediately dangerous to life and health. and can explode, with mix of air (think crash)
It is used in commercial class systems with great effort in safety... (complex and expensive) and oddly found in RV refrigerators...
so the invented Freon, to solve all that, until they found out it eats up ozone in the upper stratosphere... so the changed the product to lessen this effect or remove it.
that is the short history of Freon. (big business here in TEXAS) huge.... (Trane and all big makers here)

my next system overhaul (home) will be R-410A (im half there now.... (at the evap core) see>?

the system uses the laws of physics called the Reverse Carnot Cycle. (moves heat in side cab to the outdoors)

https://onedirectionkateupton.wordpress....not-cycle/

or simply, it's just a heat pump. (in this case 1 way)
the system works by condensing the R12 at the condenser core. up front,
the pump compresses the freon and feeds to the condenser, it's now a liquid freon R12.
next is the :
expansion valve hidden in the cab evap core box. (its a nozzle or orifice arrangement inside)
the expansion valves change the liquid to a gas, (regulated in all cases by diffr. means)
the liquid changes from a liquid to a gas and gets real cold just like a, CO2 fire extinguisher does, deployed, same effect and physics. there.
this cools the cab air and the cycle repeats.. (loop fashion)

the key factors are the correct pressure, at the lowside and high side test points (nipples)
the system is tuned to work at its best working pressures.
if not it will be weak or the hi/low will trip off line the whole system.
it is not like simple swap cooler using water that evaporates.
The freon pressures are critical.