EXHIBIT 10.5(o)

                                 PROMISSORY NOTE



$50,000.00                                                  Date: March 11, 1997



For  value   received,   the   undersigned   Rick  Bacchus  and  Philis  Bacchus
(collectively the "Promisor") each as principal,  jointly and severally, promise
to pay to the order of Refrigeration  Technology Inc. (the "Payee"), at P.O. Box
3048,  Sunland Park, New Mexico 88063,  (or at such other place as the Payee may
designate in writing) the sum of  $50,000.00  with interest from March 11, 1997,
on the unpaid  principal at the rate of 1.00 percent over prime published in the
Wall Street Journal, Eastern Edition, annually.

The unpaid  principal shall be payable over five years accrued interest shall be
payable monthly.  All payments on this Note shall be applied first in payment of
accrued interest and any remainder in payment of principal.

If any  installment  is not paid when due,  the  remaining  unpaid  balance  and
accrued interest shall become due immediately at the option of the Payee.

The Promisor  reserves the right to prepay this Note (in whole or in part) prior
to the Due Date with no prepayment penalty.

If any payment  obligation  under this Note is not paid when due,  the  Promisor
promises to pay all costs of  collection,  including  reasonable  attorney fees,
whether or not a lawsuit is commenced as part of the collection  process. If any
of the following events of default occur, this Note and any other obligations of
the  Promisor to the Payee,  shall  become due  immediately,  without  demand or
notice:

1)       the failure of the Promisor to pay the principal and any
         accrued interest in full on or before the Due Date;

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2)       the death of the Promisor(s) or Payee(s);

3)       the filing of bankruptcy proceedings involving the Promisor
         as a Debtor;

4)       the application for appointment of a receiver for the
         Promisor;

5)       the making of a general assignment for the benefit of the
         Promisor's creditors;

6)       the insolvency of the Promisor; or

7)       the misrepresentation by the Promisor to the Payee for the
         purpose of obtaining or extending credit.

This Note is secured by Quality Air stock owned by promisor and, when converted,
RTI  stock.  The Payee is not  required  to rely on the above  security  for the
payment of this Note in the case of default,  but may proceed  directly  against
the Promisor.

If any  one or  more  of the  provisions  of  this  Note  are  determined  to be
unenforceable,  in whole or in part,  for any reason,  the remaining  provisions
shall remain fully operative.

All payments of  principal  and interest on this Note shall be paid in the legal
currency of the United States. Promisor waives presentment for payment, protest,
and notice of protest and nonpayment of this Note.

No renewal or extension of this Note,  delay in enforcing any right of the Payee
under this Note,  or assignment by Payee of this Note shall affect the liability
of the Promisor.  All rights of the Payee under this Note are cumulative and may
be exercised concurrently or consecutively at the Payee's option.

This note will be replaced  with a  promissory  note after  distribution  of RTI
shares.

This Note shall be  construed  in  accordance  with the laws of the State of New
Mexico.

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Signed this 11TH day of  MARCH, 1997, at ---------------------------------------



By: /s/ RICK BACCHUS
---------------------------
        Rick Bacchus


By: /s/ PHILIS BACCHUS
---------------------------
        Philis Bacchus


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