Automotive Air Conditioning Information Forum (Archives)

Trikebent on Thu August 29, 2013 9:58 PM

Year: 1989
Make: Mazda
Model: B2200
Engine Size: 2.2l
Refrigerant Type: R134
Ambient Temp: 85
Pressure Low: 25
Pressure High: 200

I'm getting high pressure 300+ and climbing from my partially filled (12 oz in 19 capacity) R-12 conversion.

Compressor- New Alpha universal
Condenser- stock serpentine
New receiver/ dryer ever time I open the system
Expansion valve- new 2X
Evaporator- Stock
New hoses with R134 fittings

After flushing the system due to a seized compressor, evacuated to 30 in hg vacuum for 45 minutes. It held overnight. Re-vacuumed for 45 minutes (OK, overkill) then filled system with 19 oz R132. System worked great for about 1 hour, 45° vent temps on a 90° day. About an hour after the test drive I was idling in the driveway when the relief valve on the compressor let go.
I re-flushed the system and replaced the expansion valve and the relief valve. Both expansion valves flow dry air at room temp when removed and tested.
The condenser is not blocked internally- good flow thru the tubing. The fan clutch is new and working properly, good airflow. Water sprayed on the condenser slows the climb to 300 plus but does not stop it
System flushed 2 times. No dirt/debris found.
The last time I changed the ac pump oil. Old oil was 1 yr old. Vacuum did drop 1/2" in the gage. After the oil change it still has high pressure.
The system will run at 200 H / 25 Low for about 1-2 minutes them the high pressure starts to steady climb. I chicken out at 325 psi & turn off the A/C.
I'm not overcharged, there was only 12 oz in the system.
I bled the charging hose at the Gage when I connect to the Freon.
What have I missed?

Chick on Thu August 29, 2013 10:09 PM

Does your truck have an electric fan?? if so is it working properly, if not you might have to add one to get the good air flow.... You must have good air flow over the condenser is very imnportant.... If you have just a clutch fan, make sure it's it's working properly.. Hold a rag over the condenser, it should get sucked against the condenser and not fall... Clean the condenser of bugs and dirt, and the area between the radiator and condenser of leaves oil etc, do you have a fan shroud? ... Let us know how that works...hope this helps...

Also when the pressure is rising feel the inlet and outlet of the drier..have to be the same temp..If the line coming out is cooler, you have a restriction in the drier, but I feel it's airflow from what I can see......

BTW, it is possible you have a bad fan clutch (even new)...it's not uncommon....something to think about...

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

Edited: Thu August 29, 2013 at 10:47 PM by Chick

Trikebent on Thu August 29, 2013 11:23 PM

Trikebent on Thu August 29, 2013 11:26 PM

I'll try the rag test and the dryer check.

Trikebent on Wed September 04, 2013 10:16 PM

Ok:
No electric fan, stock engine driven clutch fan with stock shroud in good shape. With the engine warm and turned off, the fan will only spin 1-2 blades when flicked
Rag test- rag stuck to Evap
Dryer restriction- both in & out lines felt the same, warm to hot
No bugs, leaves, oil etc.

Tonight it did not repeat the problem, ran for about 5 minutes idling, no problems.
Air temp 85-90°F
High side 225 psi
Low 25-28 PSI
Vent temp 55°F
12 oz charge out of 19 oz

I've ordered a binary pressure switch from a 86-87 Honda civic. It is a direct swap for the Mazda low pressure switch. high off is 445 psi. I that too high?
I will be putting in an electric fan. I have room for a 14" Any recommendations on brand to buy or avoid?

Cussboy on Wed September 04, 2013 10:35 PM

The 1989 B2200 is a very good AC system, I have the 1988 here in Arizona. However, mine's still R-12. My compressor is about 10 years old, a rebuilt from this site sponsor. My truck does very well with a regular fan clutch, but it does have a 2-row radiator since my engine rebuild 2 years ago.

I'm not experienced with R134a conversions, so will not comment.

WyrTwister on Thu September 05, 2013 2:30 PM

Quote
Originally posted by: Trikebent
I'll try the rag test and the dryer check.

Have you checked function / temp at the vent , driving about 60 mph ? At highway speed , you should be getting sufficient air flow , whether the fan clutch was working or not ?

God bless
Wyr

Trikebent on Thu September 05, 2013 8:06 PM

I have not done a drive test. Too chicken I guess. I was thinking seeing if the Gage hoses were long enough to run thru the firewall and monitor while driving.

mk378 on Thu September 05, 2013 11:46 PM

Run the hoses through the gap behind the hood and tape the gauges SECURELY to the windshield so you can see from inside (you should be in the passenger's seat, have someone else drive). Make sure the hood is latched FULLY.

webbch on Fri September 06, 2013 2:22 AM

You know, I have to say that I've NEVER in my entire life seen someone driving around with a gauge set taped to their windshield. I totally see the logic in doing so, but it must be an interesting sight for other folks on the road

wptski on Fri September 06, 2013 7:46 AM

Quote
Originally posted by: mk378
Run the hoses through the gap behind the hood and tape the gauges SECURELY to the windshield so you can see from inside (you should be in the passenger's seat, have someone else drive). Make sure the hood is latched FULLY.
Even if the hood opens all the way to the windshield there still is a engine compartment seal to contend with and the hoses would be too big, I think. Maybe in the future they'll have sensors on everything and one just uses a scan tool.

Trikebent on Fri September 06, 2013 3:02 PM

If I pull the grommet were the evap lines pass thru the firewall, I think the gage lines will go thru there as well. (well protected by tape of course!) I need to see if the lines are long enough reach safely.
Any idea on what the Alpha compressors relief valves open up at?
If the binary switch opens at 445 psi, will the switch open first, or the relief valve?
I'm toying with the idea of adding a 'pusher' fan to the front of the condenser and leaving the engine driven fan in place.
Any thoughts on that approach?

94RX-7 on Fri September 06, 2013 3:26 PM

Quote
Water sprayed on the condenser slows the climb to 300 plus but does not stop it

That concerns me. Water (assuming you're not using hot water) should cause the pressures to drop immediately, and they should stay steady at that lower pressure as long as some fresh water keeps flowing. Leads me to believe you do have debris somewhere in the system creating a restriction. Where is the high pressure service port located?

Trikebent on Fri September 06, 2013 4:34 PM

Both service ports are in the hoses leading into/out of, the compressor. They are approx 3-4" from the compressor.

mk378 on Fri September 06, 2013 5:58 PM

Seized compressor could mean debris partly blocked the condenser. The serpentines have multiple small passages in the tubes similar to a parallel flow.

94RX-7 on Fri September 06, 2013 6:28 PM

Quote
Originally posted by: Trikebent
Both service ports are in the hoses leading into/out of, the compressor. They are approx 3-4" from the compressor.

With the service port in that location, you could have a restriction anywhere between the port and the expansion valve. Is there any sort of muffler or canister in the line between the compressor and condenser? If so, there could be debris hiding in there plugging things up. If not, then my money is on you still having some sort of restriction in the condenser. Did you flush it backwards when you were flushing?

445 PSI is too high of a cutoff if you're running R-12. For R-134a it isn't unreasonable.

Trikebent on Fri September 06, 2013 6:29 PM

I did flush the condenser twice. I had good flow thru the tubes when I blew thru it with dry air. It would not hurt to do it again. I will be recovering the refrigerant and installing the binary switch.

Trikebent on Fri September 06, 2013 7:06 PM

On both flushes I did the first flush backwards (From the receiver/dryer side back to the compressor side), into a clean rag to see what, if anything was there. Nothing on both flushes.
There is no muffler on this system. I did replace the receiver/dryer both times.
I am running R 134.

94RX-7 on Sat September 07, 2013 9:26 AM

Quote
Originally posted by: Trikebent
On both flushes I did the first flush backwards (From the receiver/dryer side back to the compressor side), into a clean rag to see what, if anything was there. Nothing on both flushes.

There is no muffler on this system. I did replace the receiver/dryer both times.

I am running R 134.

It sounds like you've got all the bases covered....but if the water hose won't keep the pressures under control an extra electric fan certainly won't do the trick. A stream of water will always remove more heat than a stream of air.

Trikebent on Sat September 07, 2013 11:53 AM

We may be om to something. The water I applied was from a hand pump/windex type bottle, not a garden hose. I sprayed a few oz on water, not quarts or gallons.
When people spray water, is it from a hose or squirt gun?

wptski on Sat September 07, 2013 2:13 PM

Quote
Originally posted by: Trikebent
We may be om to something. The water I applied was from a hand pump/windex type bottle, not a garden hose. I sprayed a few oz on water, not quarts or gallons.

When people spray water, is it from a hose or squirt gun?
Normally it's from a flush gun or solvent pushed by high pressure air.