• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech

Replaced switch, still no A/C

  • Thread starter Thread starter 94v6GT
  • Start date Start date Aug 5, 2008
9

94v6GT

New Member
May 13, 2006
141
0
0
Aug 5, 2008
#1
  • Aug 5, 2008
  • #1
went and bought a refill w/ gauge kit. gauge said it was full so i replaced the low pressure switch at firewall. now i see/hear compressor kick on for 1 second then off for 3 continuously.

gauge will show pressure waaaaay high!, until compressor kicks in then it drops way low.

what now
 
F

fish254

Founding Member
Sep 20, 2002
237
0
16
Brooklyn NY
Aug 5, 2008
#2
  • Aug 5, 2008
  • #2
those refill gauges dont work i had the same problem u dont have enough gass for the compressor to kick on!!
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
Aug 5, 2008
#3
  • Aug 5, 2008
  • #3
Agreed. For the low pressure reading to be valid, it has to be viewed after the compressor has been engaged for a few seconds.
 
9

94v6GT

New Member
May 13, 2006
141
0
0
Aug 5, 2008
#4
  • Aug 5, 2008
  • #4
so its still low then? ok i'll try adding. i jus didnt wanna risk anything (mainly my safety)
 

BlownFiveLiter

have car, will race....wait, it doesn't run
15 Year Member
Nov 29, 1999
3,133
18
108
Chicagoland
Aug 5, 2008
#5
  • Aug 5, 2008
  • #5
Chances are it's still low. Once the pressure equalizes across the high and low sides, the low pressure switch turns the compressor off. You can jumper the terminals in the harness to force it to run, so that it will accept more refrigerant.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
Aug 5, 2008
#6
  • Aug 5, 2008
  • #6
94v6GT said:
so its still low then? ok i'll try adding. i jus didnt wanna risk anything (mainly my safety)
Click to expand...

If you don't want to risk your safety, have a shop check it over.

Always use proper manifold gauges (they're accurate and allow you to see high-side pressure, which is huge).


If you are concerned about the mass of charge, post up your low and high side pressures, along with ambient temps.

Good luck.
 
9

94v6GT

New Member
May 13, 2006
141
0
0
Aug 6, 2008
#7
  • Aug 6, 2008
  • #7
I proceeded to empty most of the bottle into the system. the compressor continued to cycle on and off, but the A/C does blow cool now?
the gauge alternated between 45-50(off) and 25(on). i would guess ambient was around 70-75 degrees but the engine was warming(idleing 10-15 minutes)

I think the system at some point stopped accepting refrigerant. it blew the hose out of the fitting between the gauge and the bottle so i will probably jump the switch to keep it cycled 'on' and hopefully a fresh bottle will get it icey.

If these gauges are ineffective ($20 for bottle w/ guage) do i just continue filling until the compressor 'stays' on??
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
Aug 6, 2008
#8
  • Aug 6, 2008
  • #8
94v6GT said:
I proceeded to empty most of the bottle into the system. the compressor continued to cycle on and off, but the A/C does blow cool now?
the gauge alternated between 45-50(off) and 25(on). i would guess ambient was around 70-75 degrees but the engine was warming(idleing 10-15 minutes)

I think the system at some point stopped accepting refrigerant. it blew the hose out of the fitting between the gauge and the bottle so i will probably jump the switch to keep it cycled 'on' and hopefully a fresh bottle will get it icey.

If these gauges are ineffective ($20 for bottle w/ guage) do i just continue filling until the compressor 'stays' on??
Click to expand...

The low side pressure should change when the compressor is engaged (like it will go from 30 to 20 PSI, etc).

Manifold gauges are the only way to really know what's going on. You dont want your high-side reading to be too elevated.

You also don't want to just fill it till the compressor stops cycling. The best way to know what's going on is to measure the mass of refrigerant placed into the system. After that, noting high and low pressures with regard to ambient and vent temps, and using a P-T chart, can get someone close.
 
9

94v6GT

New Member
May 13, 2006
141
0
0
Aug 8, 2008
#9
  • Aug 8, 2008
  • #9
update: so i bought another refill bottle and put about 1/2 of it in. compressor still goes on and off intermitently blow A/C blows icy cold works for me!
 
You must log in or register to reply here.

Similar threads

D
1999 G/T 4.6 A/C clutch not engaging.
  • David B.
  • Apr 26, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
2
Views
266
1996 - 2004 SN95 Mustang -General/Talk- May 8, 2025
David B.
D
T
Help with a 95 5L crank no start
  • TheBubbaJoe
  • Nov 4, 2025
  • 1994 - 1995 Specific Tech
Replies
3
Views
413
1994 - 1995 Specific Tech Nov 5, 2025
AeroCoupe
M
Progress Thread mnky99 2001 V6 evap core, ac compressor, heater core replacement
  • mnky99
  • Sep 5, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
1
Views
459
1996 - 2004 SN95 Mustang -General/Talk- Sep 5, 2025
mnky99
M
J
2003, 3.8l with air conditioning problems
  • Jimb0z '03
  • Nov 3, 2024
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
6
Views
436
1996 - 2004 SN95 Mustang -General/Talk- Nov 4, 2024
Jimb0z '03
J
K
Engine 2000 Mustang GT - Fuel issue post-blown spark plug repair
  • kenster1092
  • Feb 26, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
295
SN95 4.6L Mustang Tech Mar 10, 2026
kenster1092
K
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?